7 PrOO 3H

January 29 2002

Bryan Olson Susan Svirsky EPA Project Coordinator US Environmental Protection Agency US Environmental Protection Agency co Weston Environmental Engineering EPA New England One Lyman Street One Congress Street Suite 1100 Pittsfield Massachusetts 01201 Boston Massachusetts 02114-2023

Re GE-PittsfieldHousatonic River Site Rest of River Comments on White Paper Entitled Evaluation of Agricultural Product Deer

Hunting Home Garden and Edible Wild Plant Exposure Pathways in the Lower Housatonic River Floodplain (Nov 2001)

Dear Mr Olson and Ms Svirsky

Thank you for giving us the opportunity to review the draft white paper entitled Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways in the Lower Housatonic River Floodplain (November 2001) prepared for EPAWeston At our request GEs consultants at AMEC Earth amp Environmental and BBL Sciences have prepared comments on this white paper A copy of those comments is enclosed for each of you with four extras for Susan to distribute

We would like to discuss these issues further with you as EPA continues its development work for the Human Health Risk Assessment (HHRA) for the Rest of the River We can discuss scheduling for such a discussion in connection with our upcoming technical meetings on HHRA issues In the meantime we urge EPA to take account of the enclosed comments If you have any questions about them please let me know and I will contact the authors of the comments

Very truly yours

Andrew T Silfer PE GE Project Coordinator

Enclosure 111

Bryan Olson Susan Svirsky January 29 2002 Page 2

cc Tim Conway EPA Holly foglis EPA Margaret McDonough EPA Rick Beach Weston Richard McGrath Weston J Lyn Cutler MDEP Tom Angus MDEP Susan Steenstrup MDEP Mike Carroll GE Rod McLaren GE Kevin Holtzclaw GE Kevin Mooney GE Ken Fish GE Jim Lamb BBL Sciences John Schell BBL Sciences Russ Keenan AMEC Ellen Ebert AMEC Jim Bieke Shea amp Gardner Sam Gutter Sidley Austin Brown amp Wood

Comments on EPAs Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways

in the Lower Housatonic River Floodplain

Prepared for the General Electric Company Prepared by AMEC Earth amp Environmental Inc and

BBL Sciences a Division of BBL Inc

January 29 2002

INTRODUCTION

EPA recently provided to the General Electric Company (GE) for review a draft technical document entitled Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways in the Lower Housatonic River Floodplain (Nov 2001) prepared by G Fries D Vorhees and C Butler for Roy F Weston Inc (EPAs contractor) This report (herein referenced as the White Paper) provides a proposed approach and strategy for developing methods to characterize certain exposure pathways related to PCBs in soil from the Housatonic River floodplain Specifically the White Paper describes the general approach that will be used to characterize exposure to PCBs from the consumption of agricultural products deer obtained from hunting produce from home gardens and wild plants (eg fiddlehead ferns) These exposure pathways would be used by EPA to assess current and future risks associated with floodplain PCBs in the Rest of River portion of the Housatonic

Upon review of this White Paper GE has asked AMEC Earth amp Environmental and BBL Sciences to provide comments on the proposed approach and methodology outlined therein These comments are being submitted to EPA for its consideration in developing the final assessment methodology The following comments are specific to each of the proposed exposure pathways In some cases recommendations or alternative approaches are advanced for EPAs consideration

I AGRICULTURAL PRODUCT EXPOSURE SCENARIOS

A Comments on Land Use Assumptions

1 The White Paper indicates that contamination of milk due to consumption of corn silage by dairy cows will be evaluated under both current and future use of the Housatonic floodplain (Table 1) However the available data indicate that there is no need to evaluate this milk consumption pathway at least for current use

The White Paper acknowledges that no dairy cows are currently being grazed on the Housatonic floodplain (p 3) However it states that uptake of PCBs into cows milk and consumption of such milk will be evaluated because some floodplain areas are or can be used to grow corn silage and such silage typically comprises 50-60 percent of a

lactating cows diet (p 2) Such evaluation however is not warranted by the available data at least for current use

Available sampling data of milk from cows raised on dairy farms along the Housatonic even in the more highly contaminated reaches above Woods Pond showed no detectable concentrations of RGBs in the milk samples Although these data are limited and hampered by an absence of information on detection limits they nevertheless provide some indication of a lack of PCB uptake from soil into milk Moreover corn samples recently collected from the floodplain were also largely non-detect despite the fact that co-located soil PCB concentrations ranged as high as 42 mgkg The available data thus indicate that it is unlikely that milk from dairy cows raised in this area will be contaminated In addition it is most likely that milk from dairy cows raised on the floodplain will be combined during processing with milk from cows raised in other areas diluting any possible PCB contamination well below levels of concern

In these circumstances evaluation of the milk consumption pathway is unsupported by any currently available data Hence evaluation of that pathway appears to be unnecessary and should be eliminated at least for current use conditions Future use conditions are addressed below

2 EPA should not assume the establishment of new dairy or beef cattle farms along the Housatonic without specific evidence that such use is reasonably anticipated and current information indicates that such future use is not reasonably anticipated

EPA guidance documents suggest that when considering potential exposure scenarios for risk assessment purposes only those that are reasonably anticipated future land use should be included (EPA 1991) Based on current uses and available information it is highly improbable that Housatonic floodplain properties that have not previously been or are not currently being used for raising beef and dairy cattle (at least in Massachusetts) will be used for those purposes in the future

Regional evidence suggests that dedicating property for the purposes of raising beef and dairy cows is on the decline According to representatives of the Berkshire County Soil Conservation Service agricultural activities within Berkshire County have historically been limited to properties traditionally devoted to farming In 1996 it was reported that dairy farms in the county had declined from approximately 100 to approximately 40 over the previous decade and that there was no prospect of new farms (pers comm M Grennan Berkshire County Soil Conservation Service December 17 1996) Data from a 1997 Agricultural Survey in Berkshire County indicated that while there had been 92 farms with milk cows in the county in 1987 only 68 farms had milk cows in 1997 (MAC 1997) Similarly while there were reportedly 114 farms with beef cattle in the county in 1987 only 92 farms still had beef cattle in 1997 Overall in Berkshire County the total number of farms that reported owning any type of livestock decreased from 214 in 1987 to 160 in 1997 (MAC 1997)

Start-up costs and costs associated with these types of farming are high and given the low return on investment are unlikely to be undertaken as new ventures In addition

land market values in Berkshire County make it unlikely that new land will be dedicated to farming

Thus it appears unlikely based on current information that new dairy or beef cattle farms will be established along the Housatonic in Massachusetts Accordingly it is recommended that EPA omit the exposure pathways associated with such farming in its evaluation of future land use scenarios unless there is specific evidence that such use is reasonably anticipated in a particular area

B Comments on Exposure Assumptions

1 The White Paper has not specified the exposure assumptions that will be used to model transfer of PCBs from floodplain soils into livestock or food products

The White Paper provides a summary of available sampling data and land use information and suggests the general methodology that will be used to complete the agricultural assessment However it lacks specificity about how individual pathways will be evaluated and the approaches and assumptions that will be used to estimate agricultural exposures

There are many factors that will need to be considered on a property-by-property basis For example as previously noted the White Paper indicates the exposure to dairy cows milk will be evaluated in the risk assessment due to the fact that corn silage is grown on the floodplain and that silage comprises 50 to 60 percent of a lactating cows diet (p 2) As also discussed above the currently available information does not justify including this exposure pathway in the risk assessment at all either for current or future land use However if this exposure pathway is to be retained the specific exposure assumptions to be used in the evaluation need to be specified In its current form the White Paper does not specify the amount of soil or forage that is likely to be ingested Nor does it specify how the fraction of silage or forage that originates from the floodplain area will be determined These are important factors in estimating uptake of PCBs into milk since the assumptions used can result in substantially different estimates of PCB levels in milk

The percent of silage or forage that originates from the floodplain area should be based on the fraction of the individual parcel that is contained within the floodplain and is suitable for these uses It is assumed that EPA intends to calculate this fraction on a parcel-specific basis but the White Paper does not specify how this will be done It is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This fraction can then be applied to the fraction of the diet that is represented by the silage or forage to more closely approximate exposures to floodplain contaminants Although the use of an area use factor will provide a more reasonable estimate of PCB accumulation from floodplain soil it is still an approach that has a high degree of uncertainty The impact of this

uncertainty on the development and utility of risk-based soil concentrations should be described in the assessment

In addition the White Paper indicates that when attempting to determine transfer rates for chemicals of concern (COC) to edible plants plant species will be grouped according to the expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific sampling data (p 27) It does not state what the basis for the groupings will be or which transfer rates will be assigned to which groups Because uptake of COCs by plants is highly variable and can vary by orders of magnitude as discussed below these are critical assumptions when attempting to model exposures Thus depending upon the assumptions made the results can also differ by orders of magnitude

In summary EPA should develop a revised methodology that provides more detailed information about the specific approaches and assumptions that are to be used to account for fractions of properties and crops that are located in the floodplain of the river It should also outline the specific approach that will be used to estimate plant tissue concentrations based on available sampling data Once such information has been provided we will provide comments on those assumptions

2 The White Paper indicates that the risk assessment will account for the fraction of home-produced dairy beef and poultry but does not specify the assumptions that will be used

For this risk assessment there are two factors that need to be considered in estimating exposures to PCBs through the consumption of home-produced dairy beef or poultry The first is the fraction of total dairy beef and poultry consumed within a household that is likely to be home-produced The second is the fraction of exposure of home-produced livestock that is associated with the floodplain Livestock that have no or only very limited exposure to chemicals of concern in floodplain soils will present no exposure hazard to individuals that consume their meat

Estimates of home-produced dairy beef and poultry are discussed in EPAs Exposure Factors Handbook (EPA 1997) based on short-term dietary recall data collected by the US Department of Agriculture (USDA) While these data are useful when looking at single food products they are problematic when looking at aggregate exposures to a number of food products due to the way in which the data are collected (as discussed below) In addition in most cases farms focus on one type of livestock (eg beef cattle dairy cattle or chickens) so that not all of these products are likely to be home-produced on a single farm

EPA (1997) recognizes the limitations of the short-term dietary data for use in predicting long-term consumption rates and recommends that its consumption rate estimates only be used to evaluate short-term (ie one week) exposures For looking at longer-term intake EPA recommends using seasonally adjusted homegrown intake rates (p 13-10 EPA 1997) It would be most appropriate to select home-produced consumption rates from non-metropolitan areas of the Northeastern United States Unfortunately because so few families surveyed in non-metropolitan areas of the Northeast indicated that they

consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

10

are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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Bryan Olson Susan Svirsky January 29 2002 Page 2

cc Tim Conway EPA Holly foglis EPA Margaret McDonough EPA Rick Beach Weston Richard McGrath Weston J Lyn Cutler MDEP Tom Angus MDEP Susan Steenstrup MDEP Mike Carroll GE Rod McLaren GE Kevin Holtzclaw GE Kevin Mooney GE Ken Fish GE Jim Lamb BBL Sciences John Schell BBL Sciences Russ Keenan AMEC Ellen Ebert AMEC Jim Bieke Shea amp Gardner Sam Gutter Sidley Austin Brown amp Wood

Comments on EPAs Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways

in the Lower Housatonic River Floodplain

Prepared for the General Electric Company Prepared by AMEC Earth amp Environmental Inc and

BBL Sciences a Division of BBL Inc

January 29 2002

INTRODUCTION

EPA recently provided to the General Electric Company (GE) for review a draft technical document entitled Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways in the Lower Housatonic River Floodplain (Nov 2001) prepared by G Fries D Vorhees and C Butler for Roy F Weston Inc (EPAs contractor) This report (herein referenced as the White Paper) provides a proposed approach and strategy for developing methods to characterize certain exposure pathways related to PCBs in soil from the Housatonic River floodplain Specifically the White Paper describes the general approach that will be used to characterize exposure to PCBs from the consumption of agricultural products deer obtained from hunting produce from home gardens and wild plants (eg fiddlehead ferns) These exposure pathways would be used by EPA to assess current and future risks associated with floodplain PCBs in the Rest of River portion of the Housatonic

Upon review of this White Paper GE has asked AMEC Earth amp Environmental and BBL Sciences to provide comments on the proposed approach and methodology outlined therein These comments are being submitted to EPA for its consideration in developing the final assessment methodology The following comments are specific to each of the proposed exposure pathways In some cases recommendations or alternative approaches are advanced for EPAs consideration

I AGRICULTURAL PRODUCT EXPOSURE SCENARIOS

A Comments on Land Use Assumptions

1 The White Paper indicates that contamination of milk due to consumption of corn silage by dairy cows will be evaluated under both current and future use of the Housatonic floodplain (Table 1) However the available data indicate that there is no need to evaluate this milk consumption pathway at least for current use

The White Paper acknowledges that no dairy cows are currently being grazed on the Housatonic floodplain (p 3) However it states that uptake of PCBs into cows milk and consumption of such milk will be evaluated because some floodplain areas are or can be used to grow corn silage and such silage typically comprises 50-60 percent of a

lactating cows diet (p 2) Such evaluation however is not warranted by the available data at least for current use

Available sampling data of milk from cows raised on dairy farms along the Housatonic even in the more highly contaminated reaches above Woods Pond showed no detectable concentrations of RGBs in the milk samples Although these data are limited and hampered by an absence of information on detection limits they nevertheless provide some indication of a lack of PCB uptake from soil into milk Moreover corn samples recently collected from the floodplain were also largely non-detect despite the fact that co-located soil PCB concentrations ranged as high as 42 mgkg The available data thus indicate that it is unlikely that milk from dairy cows raised in this area will be contaminated In addition it is most likely that milk from dairy cows raised on the floodplain will be combined during processing with milk from cows raised in other areas diluting any possible PCB contamination well below levels of concern

In these circumstances evaluation of the milk consumption pathway is unsupported by any currently available data Hence evaluation of that pathway appears to be unnecessary and should be eliminated at least for current use conditions Future use conditions are addressed below

2 EPA should not assume the establishment of new dairy or beef cattle farms along the Housatonic without specific evidence that such use is reasonably anticipated and current information indicates that such future use is not reasonably anticipated

EPA guidance documents suggest that when considering potential exposure scenarios for risk assessment purposes only those that are reasonably anticipated future land use should be included (EPA 1991) Based on current uses and available information it is highly improbable that Housatonic floodplain properties that have not previously been or are not currently being used for raising beef and dairy cattle (at least in Massachusetts) will be used for those purposes in the future

Regional evidence suggests that dedicating property for the purposes of raising beef and dairy cows is on the decline According to representatives of the Berkshire County Soil Conservation Service agricultural activities within Berkshire County have historically been limited to properties traditionally devoted to farming In 1996 it was reported that dairy farms in the county had declined from approximately 100 to approximately 40 over the previous decade and that there was no prospect of new farms (pers comm M Grennan Berkshire County Soil Conservation Service December 17 1996) Data from a 1997 Agricultural Survey in Berkshire County indicated that while there had been 92 farms with milk cows in the county in 1987 only 68 farms had milk cows in 1997 (MAC 1997) Similarly while there were reportedly 114 farms with beef cattle in the county in 1987 only 92 farms still had beef cattle in 1997 Overall in Berkshire County the total number of farms that reported owning any type of livestock decreased from 214 in 1987 to 160 in 1997 (MAC 1997)

Start-up costs and costs associated with these types of farming are high and given the low return on investment are unlikely to be undertaken as new ventures In addition

land market values in Berkshire County make it unlikely that new land will be dedicated to farming

Thus it appears unlikely based on current information that new dairy or beef cattle farms will be established along the Housatonic in Massachusetts Accordingly it is recommended that EPA omit the exposure pathways associated with such farming in its evaluation of future land use scenarios unless there is specific evidence that such use is reasonably anticipated in a particular area

B Comments on Exposure Assumptions

1 The White Paper has not specified the exposure assumptions that will be used to model transfer of PCBs from floodplain soils into livestock or food products

The White Paper provides a summary of available sampling data and land use information and suggests the general methodology that will be used to complete the agricultural assessment However it lacks specificity about how individual pathways will be evaluated and the approaches and assumptions that will be used to estimate agricultural exposures

There are many factors that will need to be considered on a property-by-property basis For example as previously noted the White Paper indicates the exposure to dairy cows milk will be evaluated in the risk assessment due to the fact that corn silage is grown on the floodplain and that silage comprises 50 to 60 percent of a lactating cows diet (p 2) As also discussed above the currently available information does not justify including this exposure pathway in the risk assessment at all either for current or future land use However if this exposure pathway is to be retained the specific exposure assumptions to be used in the evaluation need to be specified In its current form the White Paper does not specify the amount of soil or forage that is likely to be ingested Nor does it specify how the fraction of silage or forage that originates from the floodplain area will be determined These are important factors in estimating uptake of PCBs into milk since the assumptions used can result in substantially different estimates of PCB levels in milk

The percent of silage or forage that originates from the floodplain area should be based on the fraction of the individual parcel that is contained within the floodplain and is suitable for these uses It is assumed that EPA intends to calculate this fraction on a parcel-specific basis but the White Paper does not specify how this will be done It is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This fraction can then be applied to the fraction of the diet that is represented by the silage or forage to more closely approximate exposures to floodplain contaminants Although the use of an area use factor will provide a more reasonable estimate of PCB accumulation from floodplain soil it is still an approach that has a high degree of uncertainty The impact of this

uncertainty on the development and utility of risk-based soil concentrations should be described in the assessment

In addition the White Paper indicates that when attempting to determine transfer rates for chemicals of concern (COC) to edible plants plant species will be grouped according to the expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific sampling data (p 27) It does not state what the basis for the groupings will be or which transfer rates will be assigned to which groups Because uptake of COCs by plants is highly variable and can vary by orders of magnitude as discussed below these are critical assumptions when attempting to model exposures Thus depending upon the assumptions made the results can also differ by orders of magnitude

In summary EPA should develop a revised methodology that provides more detailed information about the specific approaches and assumptions that are to be used to account for fractions of properties and crops that are located in the floodplain of the river It should also outline the specific approach that will be used to estimate plant tissue concentrations based on available sampling data Once such information has been provided we will provide comments on those assumptions

2 The White Paper indicates that the risk assessment will account for the fraction of home-produced dairy beef and poultry but does not specify the assumptions that will be used

For this risk assessment there are two factors that need to be considered in estimating exposures to PCBs through the consumption of home-produced dairy beef or poultry The first is the fraction of total dairy beef and poultry consumed within a household that is likely to be home-produced The second is the fraction of exposure of home-produced livestock that is associated with the floodplain Livestock that have no or only very limited exposure to chemicals of concern in floodplain soils will present no exposure hazard to individuals that consume their meat

Estimates of home-produced dairy beef and poultry are discussed in EPAs Exposure Factors Handbook (EPA 1997) based on short-term dietary recall data collected by the US Department of Agriculture (USDA) While these data are useful when looking at single food products they are problematic when looking at aggregate exposures to a number of food products due to the way in which the data are collected (as discussed below) In addition in most cases farms focus on one type of livestock (eg beef cattle dairy cattle or chickens) so that not all of these products are likely to be home-produced on a single farm

EPA (1997) recognizes the limitations of the short-term dietary data for use in predicting long-term consumption rates and recommends that its consumption rate estimates only be used to evaluate short-term (ie one week) exposures For looking at longer-term intake EPA recommends using seasonally adjusted homegrown intake rates (p 13-10 EPA 1997) It would be most appropriate to select home-produced consumption rates from non-metropolitan areas of the Northeastern United States Unfortunately because so few families surveyed in non-metropolitan areas of the Northeast indicated that they

consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

10

are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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Comments on EPAs Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways

in the Lower Housatonic River Floodplain

Prepared for the General Electric Company Prepared by AMEC Earth amp Environmental Inc and

BBL Sciences a Division of BBL Inc

January 29 2002

INTRODUCTION

EPA recently provided to the General Electric Company (GE) for review a draft technical document entitled Evaluation of Agricultural Product Deer Hunting Home Garden and Edible Wild Plant Exposure Pathways in the Lower Housatonic River Floodplain (Nov 2001) prepared by G Fries D Vorhees and C Butler for Roy F Weston Inc (EPAs contractor) This report (herein referenced as the White Paper) provides a proposed approach and strategy for developing methods to characterize certain exposure pathways related to PCBs in soil from the Housatonic River floodplain Specifically the White Paper describes the general approach that will be used to characterize exposure to PCBs from the consumption of agricultural products deer obtained from hunting produce from home gardens and wild plants (eg fiddlehead ferns) These exposure pathways would be used by EPA to assess current and future risks associated with floodplain PCBs in the Rest of River portion of the Housatonic

Upon review of this White Paper GE has asked AMEC Earth amp Environmental and BBL Sciences to provide comments on the proposed approach and methodology outlined therein These comments are being submitted to EPA for its consideration in developing the final assessment methodology The following comments are specific to each of the proposed exposure pathways In some cases recommendations or alternative approaches are advanced for EPAs consideration

I AGRICULTURAL PRODUCT EXPOSURE SCENARIOS

A Comments on Land Use Assumptions

1 The White Paper indicates that contamination of milk due to consumption of corn silage by dairy cows will be evaluated under both current and future use of the Housatonic floodplain (Table 1) However the available data indicate that there is no need to evaluate this milk consumption pathway at least for current use

The White Paper acknowledges that no dairy cows are currently being grazed on the Housatonic floodplain (p 3) However it states that uptake of PCBs into cows milk and consumption of such milk will be evaluated because some floodplain areas are or can be used to grow corn silage and such silage typically comprises 50-60 percent of a

lactating cows diet (p 2) Such evaluation however is not warranted by the available data at least for current use

Available sampling data of milk from cows raised on dairy farms along the Housatonic even in the more highly contaminated reaches above Woods Pond showed no detectable concentrations of RGBs in the milk samples Although these data are limited and hampered by an absence of information on detection limits they nevertheless provide some indication of a lack of PCB uptake from soil into milk Moreover corn samples recently collected from the floodplain were also largely non-detect despite the fact that co-located soil PCB concentrations ranged as high as 42 mgkg The available data thus indicate that it is unlikely that milk from dairy cows raised in this area will be contaminated In addition it is most likely that milk from dairy cows raised on the floodplain will be combined during processing with milk from cows raised in other areas diluting any possible PCB contamination well below levels of concern

In these circumstances evaluation of the milk consumption pathway is unsupported by any currently available data Hence evaluation of that pathway appears to be unnecessary and should be eliminated at least for current use conditions Future use conditions are addressed below

2 EPA should not assume the establishment of new dairy or beef cattle farms along the Housatonic without specific evidence that such use is reasonably anticipated and current information indicates that such future use is not reasonably anticipated

EPA guidance documents suggest that when considering potential exposure scenarios for risk assessment purposes only those that are reasonably anticipated future land use should be included (EPA 1991) Based on current uses and available information it is highly improbable that Housatonic floodplain properties that have not previously been or are not currently being used for raising beef and dairy cattle (at least in Massachusetts) will be used for those purposes in the future

Regional evidence suggests that dedicating property for the purposes of raising beef and dairy cows is on the decline According to representatives of the Berkshire County Soil Conservation Service agricultural activities within Berkshire County have historically been limited to properties traditionally devoted to farming In 1996 it was reported that dairy farms in the county had declined from approximately 100 to approximately 40 over the previous decade and that there was no prospect of new farms (pers comm M Grennan Berkshire County Soil Conservation Service December 17 1996) Data from a 1997 Agricultural Survey in Berkshire County indicated that while there had been 92 farms with milk cows in the county in 1987 only 68 farms had milk cows in 1997 (MAC 1997) Similarly while there were reportedly 114 farms with beef cattle in the county in 1987 only 92 farms still had beef cattle in 1997 Overall in Berkshire County the total number of farms that reported owning any type of livestock decreased from 214 in 1987 to 160 in 1997 (MAC 1997)

Start-up costs and costs associated with these types of farming are high and given the low return on investment are unlikely to be undertaken as new ventures In addition

land market values in Berkshire County make it unlikely that new land will be dedicated to farming

Thus it appears unlikely based on current information that new dairy or beef cattle farms will be established along the Housatonic in Massachusetts Accordingly it is recommended that EPA omit the exposure pathways associated with such farming in its evaluation of future land use scenarios unless there is specific evidence that such use is reasonably anticipated in a particular area

B Comments on Exposure Assumptions

1 The White Paper has not specified the exposure assumptions that will be used to model transfer of PCBs from floodplain soils into livestock or food products

The White Paper provides a summary of available sampling data and land use information and suggests the general methodology that will be used to complete the agricultural assessment However it lacks specificity about how individual pathways will be evaluated and the approaches and assumptions that will be used to estimate agricultural exposures

There are many factors that will need to be considered on a property-by-property basis For example as previously noted the White Paper indicates the exposure to dairy cows milk will be evaluated in the risk assessment due to the fact that corn silage is grown on the floodplain and that silage comprises 50 to 60 percent of a lactating cows diet (p 2) As also discussed above the currently available information does not justify including this exposure pathway in the risk assessment at all either for current or future land use However if this exposure pathway is to be retained the specific exposure assumptions to be used in the evaluation need to be specified In its current form the White Paper does not specify the amount of soil or forage that is likely to be ingested Nor does it specify how the fraction of silage or forage that originates from the floodplain area will be determined These are important factors in estimating uptake of PCBs into milk since the assumptions used can result in substantially different estimates of PCB levels in milk

The percent of silage or forage that originates from the floodplain area should be based on the fraction of the individual parcel that is contained within the floodplain and is suitable for these uses It is assumed that EPA intends to calculate this fraction on a parcel-specific basis but the White Paper does not specify how this will be done It is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This fraction can then be applied to the fraction of the diet that is represented by the silage or forage to more closely approximate exposures to floodplain contaminants Although the use of an area use factor will provide a more reasonable estimate of PCB accumulation from floodplain soil it is still an approach that has a high degree of uncertainty The impact of this

uncertainty on the development and utility of risk-based soil concentrations should be described in the assessment

In addition the White Paper indicates that when attempting to determine transfer rates for chemicals of concern (COC) to edible plants plant species will be grouped according to the expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific sampling data (p 27) It does not state what the basis for the groupings will be or which transfer rates will be assigned to which groups Because uptake of COCs by plants is highly variable and can vary by orders of magnitude as discussed below these are critical assumptions when attempting to model exposures Thus depending upon the assumptions made the results can also differ by orders of magnitude

In summary EPA should develop a revised methodology that provides more detailed information about the specific approaches and assumptions that are to be used to account for fractions of properties and crops that are located in the floodplain of the river It should also outline the specific approach that will be used to estimate plant tissue concentrations based on available sampling data Once such information has been provided we will provide comments on those assumptions

2 The White Paper indicates that the risk assessment will account for the fraction of home-produced dairy beef and poultry but does not specify the assumptions that will be used

For this risk assessment there are two factors that need to be considered in estimating exposures to PCBs through the consumption of home-produced dairy beef or poultry The first is the fraction of total dairy beef and poultry consumed within a household that is likely to be home-produced The second is the fraction of exposure of home-produced livestock that is associated with the floodplain Livestock that have no or only very limited exposure to chemicals of concern in floodplain soils will present no exposure hazard to individuals that consume their meat

Estimates of home-produced dairy beef and poultry are discussed in EPAs Exposure Factors Handbook (EPA 1997) based on short-term dietary recall data collected by the US Department of Agriculture (USDA) While these data are useful when looking at single food products they are problematic when looking at aggregate exposures to a number of food products due to the way in which the data are collected (as discussed below) In addition in most cases farms focus on one type of livestock (eg beef cattle dairy cattle or chickens) so that not all of these products are likely to be home-produced on a single farm

EPA (1997) recognizes the limitations of the short-term dietary data for use in predicting long-term consumption rates and recommends that its consumption rate estimates only be used to evaluate short-term (ie one week) exposures For looking at longer-term intake EPA recommends using seasonally adjusted homegrown intake rates (p 13-10 EPA 1997) It would be most appropriate to select home-produced consumption rates from non-metropolitan areas of the Northeastern United States Unfortunately because so few families surveyed in non-metropolitan areas of the Northeast indicated that they

consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

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representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

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It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

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have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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lactating cows diet (p 2) Such evaluation however is not warranted by the available data at least for current use

Available sampling data of milk from cows raised on dairy farms along the Housatonic even in the more highly contaminated reaches above Woods Pond showed no detectable concentrations of RGBs in the milk samples Although these data are limited and hampered by an absence of information on detection limits they nevertheless provide some indication of a lack of PCB uptake from soil into milk Moreover corn samples recently collected from the floodplain were also largely non-detect despite the fact that co-located soil PCB concentrations ranged as high as 42 mgkg The available data thus indicate that it is unlikely that milk from dairy cows raised in this area will be contaminated In addition it is most likely that milk from dairy cows raised on the floodplain will be combined during processing with milk from cows raised in other areas diluting any possible PCB contamination well below levels of concern

In these circumstances evaluation of the milk consumption pathway is unsupported by any currently available data Hence evaluation of that pathway appears to be unnecessary and should be eliminated at least for current use conditions Future use conditions are addressed below

2 EPA should not assume the establishment of new dairy or beef cattle farms along the Housatonic without specific evidence that such use is reasonably anticipated and current information indicates that such future use is not reasonably anticipated

EPA guidance documents suggest that when considering potential exposure scenarios for risk assessment purposes only those that are reasonably anticipated future land use should be included (EPA 1991) Based on current uses and available information it is highly improbable that Housatonic floodplain properties that have not previously been or are not currently being used for raising beef and dairy cattle (at least in Massachusetts) will be used for those purposes in the future

Regional evidence suggests that dedicating property for the purposes of raising beef and dairy cows is on the decline According to representatives of the Berkshire County Soil Conservation Service agricultural activities within Berkshire County have historically been limited to properties traditionally devoted to farming In 1996 it was reported that dairy farms in the county had declined from approximately 100 to approximately 40 over the previous decade and that there was no prospect of new farms (pers comm M Grennan Berkshire County Soil Conservation Service December 17 1996) Data from a 1997 Agricultural Survey in Berkshire County indicated that while there had been 92 farms with milk cows in the county in 1987 only 68 farms had milk cows in 1997 (MAC 1997) Similarly while there were reportedly 114 farms with beef cattle in the county in 1987 only 92 farms still had beef cattle in 1997 Overall in Berkshire County the total number of farms that reported owning any type of livestock decreased from 214 in 1987 to 160 in 1997 (MAC 1997)

Start-up costs and costs associated with these types of farming are high and given the low return on investment are unlikely to be undertaken as new ventures In addition

land market values in Berkshire County make it unlikely that new land will be dedicated to farming

Thus it appears unlikely based on current information that new dairy or beef cattle farms will be established along the Housatonic in Massachusetts Accordingly it is recommended that EPA omit the exposure pathways associated with such farming in its evaluation of future land use scenarios unless there is specific evidence that such use is reasonably anticipated in a particular area

B Comments on Exposure Assumptions

1 The White Paper has not specified the exposure assumptions that will be used to model transfer of PCBs from floodplain soils into livestock or food products

The White Paper provides a summary of available sampling data and land use information and suggests the general methodology that will be used to complete the agricultural assessment However it lacks specificity about how individual pathways will be evaluated and the approaches and assumptions that will be used to estimate agricultural exposures

There are many factors that will need to be considered on a property-by-property basis For example as previously noted the White Paper indicates the exposure to dairy cows milk will be evaluated in the risk assessment due to the fact that corn silage is grown on the floodplain and that silage comprises 50 to 60 percent of a lactating cows diet (p 2) As also discussed above the currently available information does not justify including this exposure pathway in the risk assessment at all either for current or future land use However if this exposure pathway is to be retained the specific exposure assumptions to be used in the evaluation need to be specified In its current form the White Paper does not specify the amount of soil or forage that is likely to be ingested Nor does it specify how the fraction of silage or forage that originates from the floodplain area will be determined These are important factors in estimating uptake of PCBs into milk since the assumptions used can result in substantially different estimates of PCB levels in milk

The percent of silage or forage that originates from the floodplain area should be based on the fraction of the individual parcel that is contained within the floodplain and is suitable for these uses It is assumed that EPA intends to calculate this fraction on a parcel-specific basis but the White Paper does not specify how this will be done It is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This fraction can then be applied to the fraction of the diet that is represented by the silage or forage to more closely approximate exposures to floodplain contaminants Although the use of an area use factor will provide a more reasonable estimate of PCB accumulation from floodplain soil it is still an approach that has a high degree of uncertainty The impact of this

uncertainty on the development and utility of risk-based soil concentrations should be described in the assessment

In addition the White Paper indicates that when attempting to determine transfer rates for chemicals of concern (COC) to edible plants plant species will be grouped according to the expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific sampling data (p 27) It does not state what the basis for the groupings will be or which transfer rates will be assigned to which groups Because uptake of COCs by plants is highly variable and can vary by orders of magnitude as discussed below these are critical assumptions when attempting to model exposures Thus depending upon the assumptions made the results can also differ by orders of magnitude

In summary EPA should develop a revised methodology that provides more detailed information about the specific approaches and assumptions that are to be used to account for fractions of properties and crops that are located in the floodplain of the river It should also outline the specific approach that will be used to estimate plant tissue concentrations based on available sampling data Once such information has been provided we will provide comments on those assumptions

2 The White Paper indicates that the risk assessment will account for the fraction of home-produced dairy beef and poultry but does not specify the assumptions that will be used

For this risk assessment there are two factors that need to be considered in estimating exposures to PCBs through the consumption of home-produced dairy beef or poultry The first is the fraction of total dairy beef and poultry consumed within a household that is likely to be home-produced The second is the fraction of exposure of home-produced livestock that is associated with the floodplain Livestock that have no or only very limited exposure to chemicals of concern in floodplain soils will present no exposure hazard to individuals that consume their meat

Estimates of home-produced dairy beef and poultry are discussed in EPAs Exposure Factors Handbook (EPA 1997) based on short-term dietary recall data collected by the US Department of Agriculture (USDA) While these data are useful when looking at single food products they are problematic when looking at aggregate exposures to a number of food products due to the way in which the data are collected (as discussed below) In addition in most cases farms focus on one type of livestock (eg beef cattle dairy cattle or chickens) so that not all of these products are likely to be home-produced on a single farm

EPA (1997) recognizes the limitations of the short-term dietary data for use in predicting long-term consumption rates and recommends that its consumption rate estimates only be used to evaluate short-term (ie one week) exposures For looking at longer-term intake EPA recommends using seasonally adjusted homegrown intake rates (p 13-10 EPA 1997) It would be most appropriate to select home-produced consumption rates from non-metropolitan areas of the Northeastern United States Unfortunately because so few families surveyed in non-metropolitan areas of the Northeast indicated that they

consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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land market values in Berkshire County make it unlikely that new land will be dedicated to farming

Thus it appears unlikely based on current information that new dairy or beef cattle farms will be established along the Housatonic in Massachusetts Accordingly it is recommended that EPA omit the exposure pathways associated with such farming in its evaluation of future land use scenarios unless there is specific evidence that such use is reasonably anticipated in a particular area

B Comments on Exposure Assumptions

1 The White Paper has not specified the exposure assumptions that will be used to model transfer of PCBs from floodplain soils into livestock or food products

The White Paper provides a summary of available sampling data and land use information and suggests the general methodology that will be used to complete the agricultural assessment However it lacks specificity about how individual pathways will be evaluated and the approaches and assumptions that will be used to estimate agricultural exposures

There are many factors that will need to be considered on a property-by-property basis For example as previously noted the White Paper indicates the exposure to dairy cows milk will be evaluated in the risk assessment due to the fact that corn silage is grown on the floodplain and that silage comprises 50 to 60 percent of a lactating cows diet (p 2) As also discussed above the currently available information does not justify including this exposure pathway in the risk assessment at all either for current or future land use However if this exposure pathway is to be retained the specific exposure assumptions to be used in the evaluation need to be specified In its current form the White Paper does not specify the amount of soil or forage that is likely to be ingested Nor does it specify how the fraction of silage or forage that originates from the floodplain area will be determined These are important factors in estimating uptake of PCBs into milk since the assumptions used can result in substantially different estimates of PCB levels in milk

The percent of silage or forage that originates from the floodplain area should be based on the fraction of the individual parcel that is contained within the floodplain and is suitable for these uses It is assumed that EPA intends to calculate this fraction on a parcel-specific basis but the White Paper does not specify how this will be done It is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This fraction can then be applied to the fraction of the diet that is represented by the silage or forage to more closely approximate exposures to floodplain contaminants Although the use of an area use factor will provide a more reasonable estimate of PCB accumulation from floodplain soil it is still an approach that has a high degree of uncertainty The impact of this

uncertainty on the development and utility of risk-based soil concentrations should be described in the assessment

In addition the White Paper indicates that when attempting to determine transfer rates for chemicals of concern (COC) to edible plants plant species will be grouped according to the expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific sampling data (p 27) It does not state what the basis for the groupings will be or which transfer rates will be assigned to which groups Because uptake of COCs by plants is highly variable and can vary by orders of magnitude as discussed below these are critical assumptions when attempting to model exposures Thus depending upon the assumptions made the results can also differ by orders of magnitude

In summary EPA should develop a revised methodology that provides more detailed information about the specific approaches and assumptions that are to be used to account for fractions of properties and crops that are located in the floodplain of the river It should also outline the specific approach that will be used to estimate plant tissue concentrations based on available sampling data Once such information has been provided we will provide comments on those assumptions

2 The White Paper indicates that the risk assessment will account for the fraction of home-produced dairy beef and poultry but does not specify the assumptions that will be used

For this risk assessment there are two factors that need to be considered in estimating exposures to PCBs through the consumption of home-produced dairy beef or poultry The first is the fraction of total dairy beef and poultry consumed within a household that is likely to be home-produced The second is the fraction of exposure of home-produced livestock that is associated with the floodplain Livestock that have no or only very limited exposure to chemicals of concern in floodplain soils will present no exposure hazard to individuals that consume their meat

Estimates of home-produced dairy beef and poultry are discussed in EPAs Exposure Factors Handbook (EPA 1997) based on short-term dietary recall data collected by the US Department of Agriculture (USDA) While these data are useful when looking at single food products they are problematic when looking at aggregate exposures to a number of food products due to the way in which the data are collected (as discussed below) In addition in most cases farms focus on one type of livestock (eg beef cattle dairy cattle or chickens) so that not all of these products are likely to be home-produced on a single farm

EPA (1997) recognizes the limitations of the short-term dietary data for use in predicting long-term consumption rates and recommends that its consumption rate estimates only be used to evaluate short-term (ie one week) exposures For looking at longer-term intake EPA recommends using seasonally adjusted homegrown intake rates (p 13-10 EPA 1997) It would be most appropriate to select home-produced consumption rates from non-metropolitan areas of the Northeastern United States Unfortunately because so few families surveyed in non-metropolitan areas of the Northeast indicated that they

consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

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representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

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It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

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have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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uncertainty on the development and utility of risk-based soil concentrations should be described in the assessment

In addition the White Paper indicates that when attempting to determine transfer rates for chemicals of concern (COC) to edible plants plant species will be grouped according to the expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific sampling data (p 27) It does not state what the basis for the groupings will be or which transfer rates will be assigned to which groups Because uptake of COCs by plants is highly variable and can vary by orders of magnitude as discussed below these are critical assumptions when attempting to model exposures Thus depending upon the assumptions made the results can also differ by orders of magnitude

In summary EPA should develop a revised methodology that provides more detailed information about the specific approaches and assumptions that are to be used to account for fractions of properties and crops that are located in the floodplain of the river It should also outline the specific approach that will be used to estimate plant tissue concentrations based on available sampling data Once such information has been provided we will provide comments on those assumptions

2 The White Paper indicates that the risk assessment will account for the fraction of home-produced dairy beef and poultry but does not specify the assumptions that will be used

For this risk assessment there are two factors that need to be considered in estimating exposures to PCBs through the consumption of home-produced dairy beef or poultry The first is the fraction of total dairy beef and poultry consumed within a household that is likely to be home-produced The second is the fraction of exposure of home-produced livestock that is associated with the floodplain Livestock that have no or only very limited exposure to chemicals of concern in floodplain soils will present no exposure hazard to individuals that consume their meat

Estimates of home-produced dairy beef and poultry are discussed in EPAs Exposure Factors Handbook (EPA 1997) based on short-term dietary recall data collected by the US Department of Agriculture (USDA) While these data are useful when looking at single food products they are problematic when looking at aggregate exposures to a number of food products due to the way in which the data are collected (as discussed below) In addition in most cases farms focus on one type of livestock (eg beef cattle dairy cattle or chickens) so that not all of these products are likely to be home-produced on a single farm

EPA (1997) recognizes the limitations of the short-term dietary data for use in predicting long-term consumption rates and recommends that its consumption rate estimates only be used to evaluate short-term (ie one week) exposures For looking at longer-term intake EPA recommends using seasonally adjusted homegrown intake rates (p 13-10 EPA 1997) It would be most appropriate to select home-produced consumption rates from non-metropolitan areas of the Northeastern United States Unfortunately because so few families surveyed in non-metropolitan areas of the Northeast indicated that they

consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

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representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

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It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

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have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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consumed home-produced meat or dairy products estimates are not provided for this demographic group

Seasonally adjusted intake rates are provided however for consumers of home-produced meat (including meats and poultry of all types) in the Northeast According to Table 13-33 the 50th percentile of these intake rates is 0211 gkg-day which equates to an annualized average of roughly 15 gday for a 70 kg adult The 95th percentile of this distribution is 191 gkg-day (136 gday for an adult) However because of sampling methodology and the fact that EPA itself reports that it has a low level of confidence in the upper percentile values (p 13-10 EPA 1997) it is not recommended that this value be used particularly if exposures are to be aggregated

Seasonally-adjusted homegrown intake estimates for dairy products are not provided in the Exposure Factors Handbook (EPA 1997) In fact there are no data provided for home-produced dairy in three of the four regions of the US identified by EPA because of the low number of survey respondents who consumed home-produced dairy products during the survey period It is highly unlikely due to health concerns that a substantial number of individuals will consume unprocessed home-produced dairy products Rather milk produced on a single farm will most likely be combined with the milk from other dairy farms where it will be processed and pasteurized before being consumed The only individuals who might possibly consume undiluted home-produced milk would be the small number of individuals who might keep some unprocessed milk for their own use In the absence of evidence that this is occurring however consumption of home-produced milk should be eliminated as an exposure pathway

Table 13-43 (EPA 1997) indicates that 021 percent of the population in the Northeast consumes home-produced eggs Because of the low number of observations in the survey upon which the data are based EPA provides no estimated intake rates for the Northeast region If eggs are raised on a farm in the Housatonic River valley however it is probably conservative to assume that individuals living on that farm consume an average of one egg per day

In addition to considering the fraction of food consumed on a farm that is home-produced the risk assessment also needs to take into consideration the fraction of the home-produced food that is affected by PCBs in the floodplain The White Paper currently states that it will be assumed that all of the farm familys home produced food items come from the contaminated floodplain (p 32) However given the geography of the floodplain it is likely that on most properties that will be evaluated for this scenario only a small portion of the farm property is actually contained within the floodplain so that exposure of livestock to constituents in the floodplain will be limited As discussed previously EPA needs to consider the total amount of land on a given property that is likely to be used for the raising of livestock or feed and then calculate the fraction of that total land that is contained within the floodplain In doing this it is important that EPA only include those areas of land that are not regularly inundated are contoured so that they can be easily cultivated or accessed by grazing animals are readily accessible to farm machinery and are not being used for other purposes Once the total area of potentially cultivated land is identified the fraction of that land that is included in the floodplain will need to be estimated This can then be used to make a

second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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second adjustment to calculate the rate of consumption of contaminated home-produced foods

3 The White Paper states (p 31) that the risk assessment will use average and 95th percentile food consumption rates as reported by USDA and provided in the Exposure Factors Handbook While certain average consumption rates from the Exposure Factors Handbook are appropriate others are less reliable due to the bias introduced by the sampling methodology In addition as acknowledged by EPA (1997) the 95 percentile values are highly overestimated due to the sampling methodology that is used by USDA and should not be used to estimate long term exposures via these pathways

USDA food surveys are 3-day dietary recall surveys which provide a snapshot in time but are not good predictors of long-term consumption behavior Because of the length of recall period intake estimates are highly skewed to the most frequent consumers of a specific food and thus are not reliable estimates of upper bound consumption estimates EPA (1997) acknowledges this limitation of the data in every discussion of food intake rates based on USDA dietary surveys

As discussed by EPA (1997 1998) 3-day dietary records should not be used to estimate long-term rates of consumption of individual foods because many individuals consume those foods less frequently than once every three days The sampling method used by USDA records the behavior of each surveyed individual during a single 3-day sampling period However consumption of individual foods is likely to be highly variable day to day and recorded behaviors during the sampled 3-day period cannot be considered representative of behaviors over time As a result they do not provide a sound basis for estimating long-term food consumption habits This is particularly true when considering upper percentile consumption rates

Because of this inherent sampling bias the USDA data are strongly biased toward those consumers who consume a particular food with a high frequency For example all of the individuals included as consumers of asparagus in the USDA estimate consumed asparagus at least once during the 3-day sampling period To use these data to estimate annual consumption rates it is necessary to assume that the consumption behavior that occurred during the 3-day period is the same as the consumption behavior that occurs throughout every other 3-day period during the year Thus if an individual reported eating one meal of asparagus during the sampling period the extrapolation necessary to estimate long-term consumption requires the assumption that the individual continues to eat asparagus with a frequency of once every three days or as many as 122 asparagus meals per year However the individual who consumed asparagus during that sampling period may not actually be a regular asparagus consumer In fact that asparagus meal could have been the only asparagus meal that the individual consumed in an entire year Thus that persons asparagus consumption rate would be substantially overestimated Unfortunately because of the way that the USDA data are collected there is no way to determine if the behaviors reported by survey respondents during the sampling period are representative of their long-term behaviors

Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

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have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

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Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

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Conversely individuals who did not consume asparagus during the 3-day sampling period are assumed to be non-consumers of asparagus when in fact those individuals may have been consumers who coincidentally did not consume asparagus during the 3shyday sampling period Because there are no data upon which to base consumption estimates for these individuals they must be assumed to consume zero gday They may however consume asparagus with a frequency ranging from as little as zero meals per year to as much as one meal every four days or more than 90 meals per year Or with a seasonal food like asparagus they may consume it with a high frequency for a very short period of the year As with the high consumers identified in the USDA database there is no way to determine whether zero consumers are actually non-consumers individuals who consume with less frequency than once every three days or seasonal consumers

The overestimation of rates of consumption of individual foods can be demonstrated from the data provided by in the Exposure Factors Handbook (EPA 1997) In Table 13shy33 seasonally adjusted food consumption rates are provided for vegetables fruits and meats According to that table the 50th percentile rate of consumption of all vegetables is 0455 gkg-day for the Northeast region In subsequent tables however 50th

percentile values are listed for individual vegetables Although tables are presented for a total of 16 vegetables 50th percentile values are only available for the Northeast region for eight of those vegetables Even so when one sums the 50th percentile value for each of those eight vegetables the result is a total consumption rate of 327 gkgshyday This is substantially higher by a factor of more than seven than the recommended Total vegetable consumption rate provided in Table 13-33 even though it only includes half of the vegetables presented

Estimates of total vegetable consumption can be predicted fairly reliably based on short-term data due to the fact that individuals generally consume some type of vegetable daily Thus while the actual vegetables consumed may vary total vegetable consumption probably remains fairly constant For that reason the best estimates to use to estimate consumption of homegrown produce are the seasonally adjusted total consumption rates for vegetables fruits and meats as provided in Table 13-33 (EPA 1997) These seasonal adjustments take into consideration the seasonal variations in availability and consumption of homegrown produce These indicate that seasonally adjusted homegrown intake rates among consumers of homegrown food products in the Northeast are as follows

50th percentile 95th percentile Food Type (gkg-day) (gkg-day) Total Vegetables 0455 570 Total Fruit 0361 300 Total Meat 0211 191

In order to take into consideration the variability in uptake of PCBs by different types of vegetables (as discussed below) it will be necessary to further divide these consumption rate estimates into the fractions represented by different vegetable categories (eg squash leafy root etc) before calculating exposures

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

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need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

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taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

4 The White Paper states that the risk assessment will assume an exposure duration of 40 years based on subsistence farming for the RME scenario (p 32) This approach is not appropriate

There is no indication that subsistence farming is occurring along the floodplain and no indication that it will ever occur particularly in light of property values in the Housatonic River valley and development pressure there While it is assumed that EPA wants to make sure that it does not underestimate potential exposure to individuals who have farms in the floodplain there is no reason to assume subsistence parameters when subsistence behavior is not occurring Instead EPA should use the adequately protective upper bound residential exposure duration of 30 years as discussed in the Exposure Factors Handbook (EPA 1997) to evaluate the RME in the agricultural scenario

C Comments Regarding Model Assumptions

1 The proposed approach for modeling exposure to farm animals (ie using grass data as a surrogate for forage) would overestimate actual uptake of contaminants by livestock Available published field data collected at other sites indicate that levels measured in grass are not predictive of the levels observed in corn feed crops or other plant materials

The White Paper reports that the lack of detectable levels in corn necessitates the use of grass data as a surrogate to model exposures to farm animals (p 19) It fails to acknowledge however that if PCBs are not detected in the plants that would be consumed by cattle then there will be no PCB exposure to those animals While it is reasonable to use the grass data to estimate contaminant levels in grass for grazing and grasshay that may be harvested as silage it is not appropriate to use the grass data to represent PCB levels in corn silage because bioconcentration varies considerably among plant species

Corn doesnt take up PCBs the same way that grass does This is evident when one considers the site-specific vegetation data collected by EPA All corn ear samples collected from Farm 2 where PCB soil concentrations ranged from 55 to 42 ppm were non-detect indicating that the ears had taken up no PCBs despite relatively high PCB levels in soils Of the eight stalk samples analyzed five had detectable levels of PCBs These detected concentrations ranged from 0010 to 0024 mgkg Comparing these stalk concentrations with their corresponding soil concentrations results in estimated bioconcentration factors (BCFs) ranging from 000025 to 00017 When looking at the grass data collected from the former Reach 5 dairy farm however calculated BCFs are much higher In soil concentrations ranging from 38 to 21 mgkg which were similar but somewhat lower than the soil concentrations used for the corn stalk analysis grass concentrations ranged from 005 to 014 mgkg Calculated BCFs ranged from 0003 to 0030 These are higher by at least an order of magnitude indicating that the grass has a substantially higher tendency to be associated with PCBs than do the corn stalks

Low uptake by corn plants has been demonstrated in other field studies Webber et al (1994) evaluated the uptake of total PCBs and other organic contaminants by corn grown on sludge-amended soil The corn ear leaves stover and grain were analyzed

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

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are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

separately Ear leaves and stover were chopped without washing and then analyzed Wet weight BCFs ranged from 0002 to 0005 in the leaf and stover These are similar to the wet weight BCFs ranging from 00003 to 0002 that can be derived from the site-specific stalk data collected by EPA in the Housatonic River valley Wet weight BCFs in the corn grain itself were an order of magnitude lower ranging from 00001 to 00002 Similarly Strek et al (1981) calculated a fresh weight BCF for corn of 000002 while Gan and Berthouex (1994) evaluated corn grown in PCB-contaminated sludge and reported no translocation into the grain or the stover Chaney et al (1996) reported that forage crops have a dry weight uptake slope factor (or BCF) of 0001 (ugg crop dry wt per ugg soil dry wt) while grain crops have a dry weight uptake slope factor of 00001 Finally Wipf et al (1982) evaluated corn grown in TCDD contaminated soil and reported that no TCDD was detected in either the cob or the kernels

It is clear based on both published literature studies and site-specific data that PCBs and TCDD are not accumulated in the grain of the corn to any significant degree The limited contamination of the corn stover is likely due to dust adherence to the outer layers of the plant This minimal level of contamination should be taken into account when evaluating potential exposures due to consumption of corn silage by livestock

The higher level of uptake by grasses demonstrated in the site-specific data is likely due to the high surface area in grass which makes it possible for higher levels of airborne dust adherence and vapor absorption This phenomenon has been demonstrated in other field studies Kipopoulou et al (1999) evaluated uptake of PAHs by lettuce cabbage endive and leeks and found that the highest levels of uptake were in the leafy vegetables (lettuce and endive) They concluded that this was due to the large surface areas of those vegetables and their potential for more contact with vapors and dusts in the air Webber et al (1994) evaluated uptake of PCBs and other organic constituents in cabbage corn carrot roots and carrot tops The highest level of uptake was reported in the carrot foliage and was also likely due to the high surface area of that foliage

If EPA continues to model exposure to cattle it is important that it utilize relevant site-specific data on dietary uptake of PCBs in the various components of their diets It is appropriate to use PCB concentrations in grass to evaluate that portion of the cows diet that is represented by grass or hay silage if that grass or hay is grown on the floodplain It is not appropriate however to use grass samples to represent PCB exposure that will occur when cows eat corn silage or grain Instead site-specific data indicate that uptake in the corn plant is minimal with no uptake into the protected ear and minimal contamination of the corn plant Therefore corn stalk BCFs should be used to estimate uptake through this dietary component This will be a conservative assumption as PCBs were only detected in some of the stalk samples analyzed and were not detected in any of the ear samples analyzed Thus this BCF will overestimate PCB levels in the entire corn plant that is used as silage

2 The White Paper indicates that soil and grass data will be used to develop bioaccumulation factors for other plants This approach is not appropriate

There is no correlation between the reported site-specific PCB concentrations in soils and PCB concentrations in corresponding grass samples (Figure 1) In fact as soil concentrations increase it appears that BCF values decrease indicating that soil

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

10

are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

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Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

concentration is not the primary factor for estimating uptake by plants This lack of correlation between soil concentration and levels of uptake has also been demonstrated in other field studies

Levels of uptake by the plant depend on the lipid content in the plant the organic carbon content in the soil the growth period and pattern of the plant and the residence time of PCBs in soil (Strek et al 1981 Strek and Weber 1982 OConnor et al 1990 OConnor 1996) Most studies suggest that PCB uptake in the foliar portion of plants occurs primarily through vapor sorption (Miyazaki et al 1975 Iwata and Gunther 1976 Chou et al 1978 Babish et al 1979 Fries and Marrow 1981 OConnor et al 1990 Cullen et al 1996) and that PCBs are not absorbed through the roots or translocated to any significant extent (Ye et al 1991 1992 Gan and Berthouex 1994 ATSDR 1995) While it is apparent that the foliage and stems may become contaminated via the deposition of PCBs onto the cuticle it appears that internal migration may be limited due to the adsorption of PCBs to the lipophilic compounds contained in the plant cuticles (Moza et al 1976 Weber and Mrozek 1979 Strek and Weber 1982) Nonetheless the transfer of vapor-phase PCBs from air to aerial plant parts appears to be the main source of vegetation contamination from soils containing PCBs for most plants (Fries 1982 Rippen and Wesp 1993 ATSDR 1995) The degree to which PCBs will volatilize from the soil will depend on site-specific factors such as degree of organic matter and moisture content in the soil the concentration of PCBs in the soil and the volatilization potential of the individual constituents In addition field data indicate that the uptake mechanisms for the root and foliage portions of plants differ substantially Thus these types of food products should be evaluated differently

EPA needs to recognize the limitations in the grass data both in terms of its ability to reliably predict grass concentrations under different soil conditions and in terms of its applicability to other plant materials Grass data should not be used to estimate concentrations in any plant materials other than grasses that are fed to livestock While grass uptake could be considered representative of uptake by other plants with very high surface area-to-volume ratios they should not be used to estimate exposures to humans who consume homegrown produce This is because the grass samples which are likely to have had detectable PCB levels due to dust adherence to the outside of the grass rather than true uptake were not washed prior to analysis Consequently they cannot be considered representative of the levels that are likely to occur in the plant materials that are consumed by home gardeners Gardeners generally wash all produce before it is consumed and in some cases remove the outer surface of the vegetable by peeling prior to consumption As a result it can be expected that very little dust and thus very few PCBs will remain on the vegetables at the time they are consumed

The grass bioaccumulation data should not be used to estimate levels of PCBs and other constituents in plant materials that are consumed by home gardeners Instead EPA should consider both the site-specific data that have been collected for relevant food crops (acorn squash and corn grain) as well as data that are available from published field studies For those crop types for which there are no site-specific data EPA should select values from the peer-reviewed literature that are most relevant to the types of foods being consumed Tables 1 2 and 3 provide a summary of studies of uptake of PCBs by surface vegetables root crops and feed crops respectively which

10

are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

are available in the peer-reviewed literature and the bioaccumulation factors that can be derived based on them Table 4 provides a summary of available dioxinfuran uptake data for different types of plants It is recommended that when site-specific data are not available for the particular types of food crops being evaluated these studies should be used by EPA to develop uptake factors for the assessment of exposures resulting from the consumption of such homegrown food crops

3 The use of the proposed literature-based BAF of 36 to predict bovine milk and tissue PCB concentrations which is based on steady-state conditions will overpredict exposures and risks for exposure conditions in the Housatonic River floodplain

The White Paper recommends adopting the bioaccumulation factor (BAF) of 36 obtained from a study by Willett et al (1990) of lactating cows exposed to Aroclor 1254 for 67 days (p 23) This factor will be used to estimate milk and beef PCB concentrations resulting from consumption by cows of silage and grass grown on the Housatonic River floodplain Use of this BAF inherently assumes that the animals are at steady state with the food source andor soil Regarding the derivation of this BAF Fries (1996) stated Concentrations in milk fat attain an approximate steady-state concentration within 40-60 days of continuous feeding but concentrations in body fat require 6 months or more to become stable (emphasis added) Conversely Thomas et al (1999) reported that after feeding PCBs to lactating cows continuously for 15 weeks (105 days) true steady-state conditions were not attained at any time and therefore models which assume steady-state conditions to predict milk and meat concentrations should be used with care As an example of the non-steady-state conditions Thomas et al (1999) observed that while PCB intake increased during the study period (because of an increase in silage intake) the milk PCB level decreased by 25 percent

These data indicate that adopting the assumption of steady-state conditions for predicting bioaccumulation of PCBs from floodplain soil to cows milk is highly uncertain In fact as discussed above the only available data from the Housatonic River floodplain indicate that there is no appreciable accumulation of PCBs from soil to cows milk At best a BAF of 36 may be reasonable for estimating milk fat levels only under the unrealistic future use assumptions that cows in the Housatonic area are continually fed PCB-containing silage or are grazed for extended periods in the floodplain It is only under these specific conditions that the fundamental model assumption of steady-state conditions could be considered appropriate

Under typical management practices steady-state conditions will rarely if ever be achieved Situations that prevent steady-state conditions include instances where the cowscattle will be receiving intermittent doses of PCBs (variable silage levels or moving in and out of floodplain grazing areas) or when the animal is still growing (less than 2 years of age) Applying a BAF derived from steady-state assumptions to predict PCB milk and tissue concentrations will overestimate actual accumulation This will result in predicted risks that are too high or risk-based soil concentrations that are too low

The White Paper states that variability in accumulation into tissue and milk resulting from non-steady-state conditions will be blunted when the larger population of cattle (ie the entire herd) is considered (p 13) Therefore it suggests that using a statistical

11

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

representation of the PCB floodplain soil concentration (eg mean or 95 UCL on the mean) in the accumulation model will minimize the potential error because it will be used to estimate PCB levels in a population of animals rather than individual cows In other words the White Paper concludes that any concerns about steady-state conditions will be mitigated by the dilution of these non-steady-state animals by the larger population While this would be true if only a few of the animals that are potential sources of human food items failed to meet the model requirement of steady state the converse is more likely true That is only a few if any of the animals will ever achieve steady state with their food source (grass silage or soil) As such the steady-state model currently proposed in the White Paper will overestimate accumulation in all animals that do not satisfy the specific model conditions This is likely to include every animal Consequently considering a large animal population will not reduce this overestimation Instead for either future or current use exposure conditions in the Housatonic River floodplain the accumulation model is inherently flawed

Non-steady-state kinetic models are not readily available although there are certain situations where these conditions have been modeled (eg Wilson et al 2001 Avantaggio et al 1997) In these models long-term intakes are viewed as a series of individual events which vary over time (ie non-steady-state) PCB concentrations in blood or other tissue can be modeled based on time-dependent factors such as short term variations in exposures by using a pharmacokinetic model and making certain assumptions about the half-life of PCBs We recommend that EPA investigate the applicability of these models before simply assuming steady-state conditions

In summary the application of a BCF of 36 which was derived under steady-state experimental conditions to model proposed future use scenarios in which the animals are not constantly exposed to PCBs is overly conservative and inherently flawed The magnitude of this error cannot be estimated at this time but it will certainly result in substantial overestimates of risk If EPA decides to retain this exposure pathway and if non-steady-state models do not prove useful then at a minimum EPA should explicitly recognize the uncertainty and substantial overestimate in risk estimates resulting from this unlikely pathway so that the risk managers can realistically evaluate the implications of these estimates for future action

Finally the White Paper further confuses the situation by stating that a BCF of 36 will be used for PCB mixtures but then providing a wide range of congener-specific BCFs from a number of studies (Table 12) It is not clear if or how EPA intends to use these values However the calculation and summing of BCFs on a congener-specific basis would only inject an additional level of uncertainty into an already highly uncertain parameter Hence we urge EPA not to use such congener-specific BCFs

4 The White Paper indicates that the uptake of dioxins and furans in milk and beef will be estimated using a BCF approach that incorporates variable BCFs for individual congeners (Table 12) If risk assessors use 12 the detection limit for those congeners that are non-detect this approach is likely to result in highly overestimated concentrations in milk and beef

12

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

It is assumed that EPA intends to develop these BCFs on a parcel- or reach-specific basis using dioxinfuran concentrations measured in soils It is very likely however that many if not most of the individual dioxin and furan congeners will be below levels of detection While the proposed approach is not specified in the report there has been some indication at recent meetings that EPA intends to calculate the levels of dioxinsfurans in beef and milk by using Vz the detection limit to represent concentrations of those congeners that were not detected in sampling This approach is likely to result in a highly uncertain BCF that substantially overestimates levels in milk and beef because in using it it is assumed that all 2378-substituted congeners are present In fact it is very likely that many congeners may not be present in floodplain soils and those that are may not be present at concentrations as high as 14 the detection limit Thus the approach will overestimate the amount of dioxins and furans in the beef and milk

Clearly the best approach for evaluating potential exposures through the consumption of milk or beef is to collect site-specific data on dioxinfuran levels in milk and meat Given however that these exposures are hypothetical future exposures this approach is not feasible Thus if bioaccumulation factors are derived on a congener-specific basis based on soil concentrations it will be important that the resulting milk and beef PCB concentrations are compared with literature-based BCFs that have been derived by a number of researchers to provide a reality check Literature-based studies have indicated that bioconcentration factors for dioxinsfurans to milk fat and beef fat are on the order of 4 to 6 (Jensen and Hummel 1982 Fries and Paustenbach 1990 McLachlan et al 1990 EPA 1994 Firestone et al 1979) Currently EPA (1999) supports the use of a BCF of 5 to provide a conservative estimate of dioxinfuran concentrations in milk fat If EPAs site- and congener-specific estimates yield concentrations in milk and beef fat that are substantially different from those that would result from the use of published BCF values the approach should be discarded and literature-based values should be used instead to reduce uncertainty in the estimates

II DEER HUNTING

1 The White Paper states that exposures to deer will be evaluated using the same approach as that used to evaluate exposures to beef cattle (p 17) These assumptions are not appropriate for characterizing exposure to deer and should not be used to evaluate this potential exposure pathway

The behavior of wild deer is very different from the behavior of beef cattle Deer have very large home ranges (eg 2 to 3 square miles) and feed on a variety of woody deciduous plants and coniferous growth They tend to feed on twigs and strip young bark in addition to grazing on grasses herbs mushrooms fruits nuts forbs (herbaceous plants other than grasses) and sedges (grasslike herbaceous plants commonly found in wet or saturated conditions) (DeGraaf and Rudis 1983) Crawford (1982) noted that the deers diet consisted primarily of easily digested plants or parts of plants including as much as 75 forbs in late spring hardwood leaves and forbs in the summer and mostly mushrooms and hardwood leaves in the autumn Thus their feeding profile and potential for exposure to PCBs is very different from that of farm animals In addition it is very likely that the floodplain will only represent a very small portion of their feeding range If exposure to deer must be modeled all of these factors

13

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

need to be considered species-specific dietary factors need to be derived and exposures need to be corrected for the portion of home range that falls within the floodplain in each area evaluated

To provide a more accurate estimate of risks it would be preferable to sample venison from deer obtained from floodplain areas by local hunters to determine whether there are detectable levels of PCBs or dioxinsfurans in the meat If there are no detectable levels the pathway should be eliminated from the risk assessment If levels are detected these levels should be used as the exposure point concentrations for the risk evaluation instead of using modeled tissue levels

III HOME GARDENING

1 The White Paper indicates that grass samples will be used as surrogates to determine the level of COCs in some homegrown produce (p 27) As discussed previously such an approach will substantially overestimate exposures to consumers of homegrown produce

As acknowledged in the White Paper (p 26) and discussed previously PCBs and TCDDFs are not efficiently transferred from soil to plants There are a number of variables that influence the level of transfer that will occur These include the chemicalphysical characteristics of the chemicals of concern (vapor pressure partition coefficients) the organic carbon content in the soil and the characteristics of the plants (including growing period height surface area-to-volume ratio lipid content) These differences in uptake are well demonstrated in the site-specific data that have been collected from the floodplain which clearly show that uptake in squash and grass are relatively high while uptake in fiddleheads is low and uptake in corn is minimal In addition the amount of such chemicals that will actually be consumed will depend upon the way in which the plants are handled and prepared prior to consumption All of these factors should be considered in the risk assessment

The White Paper indicates that in order to develop exposure point concentrations in homegrown produce species of plants will be grouped according to expected COC transfer rates and then a transfer factor will be assigned to each group using site-specific information for corn squash fiddlehead ferns and grass (p 27) As noted above (Comment IB1) the methodology that will be used to make these groupings and assignments is not specified These assignments are critical due to the fact that transfer rates based on site-specific data vary by more than two orders of magnitude Site-specific data and published literature field studies indicate that there are substantial variations in uptake depending upon the crop being grown As a result it is important that EPA not over-simplify the assessment by arbitrarily assigning transfer factors without basis In addition as also discussed previously EPA should not use the grass samples as surrogates for any of the plant species consumed by humans as they are not representative of levels likely to be encountered in vegetables that are consumed

Field studies have shown that uptake of PCBs and TCDDF by carrots differs substantially than uptake by other root crops In addition uptake of these compounds by surface vegetables differs substantially from root crops Even among surface vegetables there is considerable variation with lettuce and other leafy vegetables

14

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

taking up considerably more RGBs than do broccoli cabbage or peppers Finally while there appear to be higher levels of uptake by certain members of the squash family this increased uptake is not demonstrated for other related squash species For these reasons the evaluation of homegrown produce should take into consideration the variability in uptaketransfer into different plant types and make assignments accordingly

IV CONSUMPTION OF WILD PLANTS

1 The White Paper reports that the potential consumption of wild plants such as fiddlehead ferns will be evaluated in this risk assessment (p 5) This approach is unnecessary because uptake of PCBs by fiddleheads is very low (as shown in Table 7 of the White Paper) and the season for harvesting and consuming fresh fiddleheads is very short making potential for exposure very limited If however EPA continues to evaluate fiddleheads it is important that the exposure scenario developed reflect realistic fiddlehead consumption practices

Fiddlehead ferns are only available for harvesting for a short period of time (one to two weeks) during the spring Thus consumption of fresh ferns is only likely to occur for a period of two or three weeks It is possible that some individuals may freeze or can fresh ferns for consumption later in the year but the number of individuals who do this is likely to be very small Because of their limited availability it is likely that annualized consumption is going to be lower than it is for other dark green vegetables such as homegrown spinach or broccoli In addition available sampling data indicate that ferns are not taking up PCBs to any appreciable extent

If EPA continues to evaluate fiddlehead fern consumption it is important that the exposure scenario reflect realistic exposure conditions For the typical individual fiddlehead consumption will only occur during the two or three weeks that they are available in the spring Because fiddleheads tend to be gritty and often have small worms in their coils they must be unwound and well washed prior to consumption Thus only PCB data for washed fiddleheads should be included in the exposure point concentrations for this exposure pathway

2 While the White Paper also mentions the possible evaluation of other wild plants (p 5) there are no data available for other wild edible plant materials upon which to base a risk assessment In addition it is highly likely that PCB concentrations in other edible plant materials (eg nuts and berries) will be even lower than concentrations in fiddleheads due to substantially less potential for contact with PCBs in floodplain soils and sediments Thus evaluation of fiddlehead ferns should provide a reasonable surrogate for any other wild plants that are consumed from the floodplain

The evaluation of other types of wild plants is unnecessary and will yield highly uncertain results The other types of wild plants that are likely to be consumed from the floodplain are wild berries and perhaps some nuts There are however no data available to conduct such an assessment The low levels of uptake of PCBs in fiddleheads which grow in the mucky banks of the river (and thus would be expected to

15

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

have the highest potential for uptake of all wild plant species consumed by humans) indicate that uptake in other plants further removed from the sediments will be even lower Nuts growing in the floodplain area would be protected from any contact with dust or vapor by their hard inedible shells Thus potential for exposure to PCBs in these other wild plants is very low

In addition the White Paper states that the intake of wild plants will be evaluated using consumption rates similar to those provided for homegrown produce (p 30) This is an inappropriate assumption Wild plants are highly seasonal and unlike homegrown produce are only available for a very short period of time (days to weeks) It is not reasonable to assume given this limited availability that rates of consumption of wild plants are similar to consumption of home-cultivated produce for which multiple plantings over the season are common thus artificially prolonging the growing season Instead if wild plants are evaluated they should be evaluated with consideration for the very short period during which they are actually available

REFERENCES

ATSDR 1995 Toxicological Profiles on CD-ROM Polycyclic Aromatic Hydrocarbons (PAHs) US Department of Health and Human Services Agency for Toxic Substances and Disease Registry Atlanta GA August

Avantaggio JD PS Price SM Hays and ML Gargas 1997 Use of microexposure and toxicokinetic modeling to estimate polychlorinated biphenyl (PCB) concentrations in the blood of anglers who consume contaminated fish Toxicologists 361441

Babish JA GS Stoewsand AK Furr TF Parkinson CA Bache WH Gutenmann PC Wszolek and DJ Lisk 1979 Elemental and polychlorinated biphenyl content of tissues and intestinal hydrocarbon hydroxylase activity of guinea pigs fed cabbage grown on municipal sewage sludge J Aghc Fd Chem 27399-402 (Cited in Sawhney and Hankin 1985)

COM 2000 Report to B von Gunten Michigan Department of Environmental Quality from Y Crooke concerning residential crop and soil sampling in Kalamazoo and Allegan Counties Michigan Camp Dresser amp McKee (CDM) Detroit Ml September 21

Chaney RL JA Ryan and GA OConnor 1996 Organic contaminants in municipal biosolids Risk assessment quantitative pathway analysis and current research priorities Sci Total Environ 185187-216

Chou SF LW Jacobs D Penner and JM Tiege 1978 Absence of plant uptake and translocation of polybrominated biphenyls (PBBs) Environ Health Perspect 239shy12 (Cited in Sawhney and Hankin 1985)

Crawford HS 1982 Seasonal food selection and digestability by tame white-tailed deer in central Maine J Wildlife Management 46(4)974-982

16

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

Cullen AC D J Vorhees and LR Altshul 1996 Influence of harbor contamination on the level and composition of polychlorinated biphenyls in produce in Greater New Bedford Massachusetts Environmental Science and Technology 30(5)1581-1588

DeGraaf RM and DD Rudis 1983 New England Wildlife Habitat Natural History and Distribution US Department of Agriculture Northeastern Forest Experiment Station Technical Report NE-108

EPA (US Environmental Protection Agency) 1991 Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions

EPA 1994 Estimating Exposures to Dioxin-Like Compounds Vol III Site-Specific Assessment Procedures Review Draft US Environmental Protection Agency Office of Research and Development Washington DC EPA6006-88005Cc

EPA 1997 Exposure Factors Handbook US Environmental Protection Agency Office of Health and Environmental Assessment EPA600P-95002Fa Washington DC

EPA 1998 Ambient Water Quality Criteria Derivation Methodology Human Health Technical Support Document Final Draft EPA822B-98005 July

EPA 1999 Risk Analysis for the Round Two Biosolids Pollutants Prepared for US Environmental Protection Agency Office of Water Health and Ecological Criteria Division by Abt Associates Inc Bethesda MD December

EPA 2001 Unpublished soil and vegetable sampling from the Housatonic River floodplain

Firestone D M Glower AP Borsetti RH Teske and PE Long 1979 Polychlorinated-p-dioxin and pentachlorophenol residues in milk and blood of cows fed technical pentachlorophenol J Agric Food Chem 271171

Fries GF and GS Marrow 1981 Chlorobiphenyl movement from soil to soybean plants J Agric Fd Chem 29757-759 (Cited in Fries 1982)

Fries GF 1982 Potential polychlorinated biphenyl residues in animal products from application of contaminated sewage sludge to land J Environ Qua 11(1)14-20

Fries GF and DJ Paustenbach 1990 Evaluation of potential transmission of 2378-tetrachlorodibenzo-p-dioxin contaminated incinerator emissions to humans via food J Toxicol Environ Health 291-43

Fries GF 1996 Ingestion of sludge applied orgainc chemicals by animals Sci Total Environ 18593-108

Can DR and PM Berthouex 1994 Disappearance and crop uptake of PCBs from sludge-amended farmland Water Environ Res 6654-69

17

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

Iwata Y and FA Gunther 1976 Translocation of the polychlorinated biphenyl Aroclor 1254 from soil into carrots under field conditions Arch Environ Contam Toxicol 444shy59

Jensen D and R Hummel 1982 Secretion of TCDD in milk and cream following the feeding of TCDD to lactating dairy cows Bull Environ Contam Toxicol 29(4)440-446

MAC 1997 Massachusetts Agricultural Census Agricultural Census for Berkshire County MA httpgovinfokerrorstedu

McLachlan MS H Thoma M Reissinger and Ol Hutziner 1990 PCDDF in an agricultural food chain Part 1 PCDDF mass balance of a lactating cow Chemosphere 201013-1020

Miyazaki A T Holta J Katayama and Y Kimura 1975 Absorption and translocation of PCB into crops Osaka-fu Norin Gijutsu Senta Kenkyu Hokoku 12135shy142 (Cited in Sawhneyand Hankin 1985)

Moza P I Weisgerber and W Klein 1976 Fate of 22-dichlorobiphenyl-14C in carrots sugar beets and soil under outdoor conditions J Agric Fd Chem 24(4)881-883

OConnor GA D Kiehl GA Eiceman and JA Ryan 1990 Plant uptake of sludge-borne PCBs J Environ Qua 19113-118

OConnor GA 1996 Organic compounds in sludge-amended soils and their potential for uptake by crop plants The Science of the Total Environment 18571-91

Rippen G and H Wesp 1993 Kale uptake of PCDDPCDF PCB and PAH under field conditions importance of gaseous dry deposition Proceedings of Dioxin 93 Organohalogen Compounds 12111-114

Sawhney BL and L Hankin 1984 Plant contamination by PCBs from amended soils J Food Prot 47(3)232-236

Strek HJ JB Weber PJ Shea E Mrozek Jr and MR Overcash 1981 Reduction of polychlorinated biphenyl toxicity and uptake of carbon-14 activity by plants through the use of activated carbon J Agric Fd Chem 29288-293

Strek HJ and JB Weber 1982 Behaviour of polychlorinated biphenyls (PCBs) in soils and plants Environ Pollut (Series A) 28291

Thomas GO AJ Sweetman and KC Jones 1999 Input - output balance of polychlorinated biphenyls in a long-term study of lactating cows Envrion Sci Technol 33104-112

Webber MD RI Pietz TC Granato and ML Svoboda 1994 Organic chemicals in the environment Plant uptake of PCBs and other organic contaminants from sludge-treated coal refuse J Environ Qua 231019-1026

18

Weber JB and E Mrozek 1979 Polychlorinated biphenyls phytotoxicity absorption and translocation by plants and inactivation by activated carbon Bull Environ Contam Toxicol 23412

Wilson ND PS Price and DJ Paustenbach 2001 An event-by-event probabilistic methodology for assessing the health risks of persistent chemicals in fish A case study at the Palos Verdes Shelf J Toxicol Environ Health 62595-642

Willett LB TY Liu and GF Fries 1990 Reevaluation of polychlorinated biphenyl concentrations in milk and body fat of lactating cows J Dairy Sci 732136-2142

Wipf H-K E Homberger N Neuner UB Ranalder W Vetter and JP Vuilleumier 1982 TCDD levels in soil and plant samples from the Seveso area In Chlorinated Dioxins and Related Compounds O Hutzinger et al(eds) New York NY Pergamon Press 115-126

Ye Q RK Puri S Kapila WR Lower and AF Yanders 1991 Studies on uptake of PCBs by Hordium Vulgare (barley) and Lycopersicon esculentum (tomato) Chemosphere 23(8-101397-1406

Ye Q Puri RK Kapila S et al 1992 Studies on the transport and transformation of PCBs in plants Chemosphere 25(7-10) 1475-1479

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Table 4 Comparison of Field Studies of DioxinFuran Uptake

Surface Vegetables Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn kernels 0 Grass 0

Silverbeet 0 Millet 0 Sage 0

Cauliflower 0 Chicory 0

Cabbage 0 Cucumber 0

Hulsteret al 1994 TCDD Squash 001

Root Vegetables Author Chemical CropPlant BCF

Briggset al 1982 TCDD Root crops (except carrots) 001

Wipf etal 1982 TCDD Carrots 005

Mulleretal 1993 TCDDeq Carrot cortex and stele 0 Carrot peel 005

Feed crops Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn sheaths 00008 TCDD Oats 0 TCDD Vetch 0

Facchetti et al (1986) TCDD Maize 0 TCDD Bean plants 0

u U BO S

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to ffl nbullraquo

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o if sect sect 8 8 5|0 08O 0 0 deg 0 0 0 deg 0 0pound o

o U

u ^uffl s

AI m (UCD bullc bull e t c pound o o o ID (O

0) o a a 8 8 - 5 8 0 O k L_ w1 0 0 deg 0 0 deg 0 0 O Oo opoundgt I 8 0 o S 0 0

poundl z z z z z j shy0

iOOgt 01

sect cf LU CC

gtlt JQ

bullg a

Car

rots

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tato

es

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sera

dish

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l

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rot

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e s

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mm

endl

rrot

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ak

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ei

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TJ bullg g TJ TJ Q 5 5 CD ltv agt (u 35 CD ltU 0) 0gt (D Q) c w TJ TJ TJ TJ O TJ TJ TJ T) TJ TJ TJ O O mdash o c

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CO CO LJf

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0

1

Table 4 Comparison of Field Studies of DioxinFuran Uptake

Surface Vegetables Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn kernels 0 Grass 0

Silverbeet 0 Millet 0 Sage 0

Cauliflower 0 Chicory 0

Cabbage 0 Cucumber 0

Hulsteret al 1994 TCDD Squash 001

Root Vegetables Author Chemical CropPlant BCF

Briggset al 1982 TCDD Root crops (except carrots) 001

Wipf etal 1982 TCDD Carrots 005

Mulleretal 1993 TCDDeq Carrot cortex and stele 0 Carrot peel 005

Feed crops Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn sheaths 00008 TCDD Oats 0 TCDD Vetch 0

Facchetti et al (1986) TCDD Maize 0 TCDD Bean plants 0

u (B (0

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0 0 CM 80 0 sect S 2 8 o oil 0 O CO Oo O deg 0 CM CM

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pound 0 0 0 0 u

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bean

sN

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rep

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CO 75 75 o o o 73 73 o 0 0 8 O) o Z Z Z Z Z Z 0gt co bullc2 re

0 o ri

laquoo a E Ere co Imdash

COCO

CO CO LJf

COCO

CO CO

COCO

CO CO If TpoundS 1 SQ) C ogt

CL 0) CM CM CO

75 re CL a bullo pound OL CL CL 0shyC n c5 pound 1 0 0 amp

Sb

re re 1shyS S ltS JS h- 1- m CO 8 8 00 I ^^ i re 55 5

c c

(mdash pound E s

o

imdashTCO re re

x Jpound 0)

o N ST e

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cula

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by

o

a

o 1 S

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c

0

1

Table 4 Comparison of Field Studies of DioxinFuran Uptake

Surface Vegetables Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn kernels 0 Grass 0

Silverbeet 0 Millet 0 Sage 0

Cauliflower 0 Chicory 0

Cabbage 0 Cucumber 0

Hulsteret al 1994 TCDD Squash 001

Root Vegetables Author Chemical CropPlant BCF

Briggset al 1982 TCDD Root crops (except carrots) 001

Wipf etal 1982 TCDD Carrots 005

Mulleretal 1993 TCDDeq Carrot cortex and stele 0 Carrot peel 005

Feed crops Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn sheaths 00008 TCDD Oats 0 TCDD Vetch 0

Facchetti et al (1986) TCDD Maize 0 TCDD Bean plants 0

Table 4 Comparison of Field Studies of DioxinFuran Uptake

Surface Vegetables Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn kernels 0 Grass 0

Silverbeet 0 Millet 0 Sage 0

Cauliflower 0 Chicory 0

Cabbage 0 Cucumber 0

Hulsteret al 1994 TCDD Squash 001

Root Vegetables Author Chemical CropPlant BCF

Briggset al 1982 TCDD Root crops (except carrots) 001

Wipf etal 1982 TCDD Carrots 005

Mulleretal 1993 TCDDeq Carrot cortex and stele 0 Carrot peel 005

Feed crops Author Chemical CropPlant BCF

Wipf etal 1982 TCDD Corn sheaths 00008 TCDD Oats 0 TCDD Vetch 0

Facchetti et al (1986) TCDD Maize 0 TCDD Bean plants 0