Brominated Diphenyl Ether Results from EPA’s 2006 - 2007

Targeted National Sewage Sludge Survey

Harry McCarty, CSCand

Rick Stevens, USEPA

DisclaimerThis presentation has not been subjected to formal review by EPA, and therefore does not reflect official EPA policies or conclusions.

The views expressed here are those of the authors.

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Background• Sewage sludge is also known as

“biosolids”

• Defined in USEPA regulations as a solid, semi-solid, or liquid residue generated during treatment of domestic sewage in a treatment works (40 CFR 503)

• By definition, it does not include residuals from treatment of industrial wastewater

Regulatory History• In the U.S., the Clean Water Act places limits on

the pollutants in effluent discharges• Historically, the limits began with 126 “priority

pollutants,” which include metals and common organic chemicals

• There are over 16,000 publicly owned treatment works (POTWs) in the U.S., and every plant is subject to Federal, State, and sometimes local, regulations on its effluent discharge and its sludge

• Separate regulations exist for effluents discharged from industrial wastewater treatment facilities

New and Emerging Contaminants

• EPA continues to investigate additional pollutants, including various “new and emerging” contaminants

• Among those “new and emerging” contaminants are the polybrominated diphenyl ethers (PBDEs) that are used as flame retardants in various products

• Other new contaminants of interest include drugs, steroids, hormones, and other personal-care products, collectively called PPCPs

National Sewage Sludge Surveys• EPA has conducted 3 national surveys:

– 1988 - 1989, examining over 400 pollutants (organics and metals) in samples from 174 POTWs

– 2001, examining PCDDs, PCDFs, and 12 “toxic” PCB congeners in samples from 94 POTWs

– 2006 - 2007, examining selected metals, anions, semivolatile organics, and other contaminants in samples from 74 POTWs

• Each survey designed to obtain unbiased national estimates of pollutant concentrations in final sludge products

Sludge Surveys (cont.)• 1988 - 1989 survey lead to the 1992

numerical limits on 10 metals in sewage sludge managed through land application, surface disposal, and incineration

• 2001 survey lead to the conclusion that:“neither numerical limitations nor requirements for

management practices are currently needed to protect human health and the environment from reasonably anticipated adverse effects from dioxin and dioxin-like compounds in land-applied sewage sludge”

2006 - 2007 Sludge Survey

• Designed to provide data for a small set of anions, metals, and semivolatile organics for which new human health benchmark data are available

• Expanded to include additional contaminants, including the PBDEs and PPCPs

Target POTW Population

• Plant existed in 2002 or 2004

• Flow rate ≥1 million gallons per day (MGD)

• Employs at least secondary treatment

• Produces a final treated biosolid product

• Not known to employ a pond or lagoon as the final stage of treatment, and

• Located in the contiguous United States

Target POTWs (cont.)

• 16,255 POTWs nationwide

• 3337 POTWs that meet the definition of the target population

• EPA selected a national sample of 80 POTWs from the 3,337 facilities in the target population

• Random sampling design stratified for flow

Stratification by Flow• 1 to 10 MGD, representing approximately

75% of the POTWs nationwide

• 10 to 100 MGD, representing approximately 15% of the POTWs nationwide

• >100 MGD, representing approximately 10% of the POTWs nationwide

National Coverage – POTWs in 37 States

Sample Collection

• CSC staff sampled at 73 POTWs between August and December 2006

• Sampling delayed at 1 POTW until April 2007, due to repairs

• 6 POTWs in the original 80 were not sampled:– Did not produce a final sludge product (partial

treatment only), or– Used a lagoon that was not yet mature

Sample Collection (cont.)• 74 POTWs and 78 sludges in total

– Collected samples of two products at each of 4 POTWs (multiple treatment lines)

– Also collected field duplicate samples at 6 POTWs, as a check on sampling procedures

• At each plant, CSC collected– 4 500-mL wide mouth HDPE jars (for anions

and metals analyses) and – 8 500-mL or 1-L wide-mouth glass jars (for

organics, including PBDEs)

Sample Shipment• Given logistics of shipping samples from 74

sites to multiple labs, all samples were sent to an EPA Sample Repository in Baltimore, MD, and stored frozen

• Once 15-20 sites were sampled, batches of frozen samples were shipped to 3 contract labs, and a group of collaborators including 2 EPA labs and 3 university labs

• Only the 3 contract labs, 1 EPA lab, and 1 university lab received every sample

Sampling Summary• 12 samplers

• 107 days of travel

• 46 one-way airline flights

• 19,419 miles driven

• 1,002 jars of sludge collected

• Over 300 coolers shipped one way

• Over 500 jars of sludge shipped to 8 labs

PBDE Analysis• Samples for PBDE analyses were held frozen

for about 1 year before being shipped to lab• Used EPA Method 1614, a high resolution

GC/MS procedure employing isotope dilution• Originally targeted the 45 PBDE congeners or

coeluting congener pairs listed in the method• Due to the complexity of the matrix and

concentrations present, scaled back to 11 congeners

11 Target Congeners

BDE-028 BDE-099 BDE-154

BDE-047 BDE-100 BDE-183

BDE-066 BDE-138 BDE-209

BDE-085 BDE-153

Yellow indicates the 8 congeners identified in the method as being of potential environmental or public health significance (4th Annual Workshop on Brominated Flame Retardants in the Environment, June 2002)

Sludge is a “challenging” matrix!

Study-Specific Modifications

• Reduce sample size from 10 g to 0.2 g, dry weight (to stay within calibration range)

• Extract samples before adding labeled compounds (to avoid diluting them out)

• Concentrate extract to 10-mL volume and take only 1 mL through silica gel, GPC, and alumina cleanups (to avoid overloading)

• Spike that 1 mL with labeled compounds (to compensate for losses during cleanup)

• Retain the other 9 mL for dilutions or more cleanups, if needed

Potential Ramifications• Reduced sample size could affect

sensitivity

• Concern about representativeness of aliquot analyzed

• Extraction efficiency not accounted for by isotope dilution, so added matrix spike samples (MS/MSD pair) with each extraction batch

Analytical Reality• Sensitivity generally was not an issue

– 9 of 11 congeners reported in all 84 samples– BDE-209 detected in 83 samples– BDE-138 only detected in 56 samples– Many samples required significant dilutions to

bring results within calibration range

• Representativeness of a 0.2-g sample is a concern, but probably no more so than a 1-L jar versus a 1-million gallon tank or a 100-foot long pile

Analytical Reality (cont.)• MS/MSD analyses

– Recovery calculations affected by high background concentrations in some samples

– Calculation problem not unique to PBDEs, or to this study

• CSC performed alternative recovery calculations– Eliminated any chance of negative recoveries– Revised recoveries range from 52 to 172%– Revised RPDs range from 0 to 58%

Results

(with apologies to Dick Orkin and Chickenman)

They’re everywhere!

They’re everywhere!

Keep in mind

Summary Data

Analyte Count

Concentration (µg/kg, dry weight)

Minimum Maximum Mean1 Mean2

BDE-028 84 2.2 160 15 13

BDE-047 84 73 5,000 709 709

BDE-066 84 1.8 110 17 16

BDE-085 84 3.2 150 28 28

BDE-099 84 64 4,000 703 716

BDE-100 84 13 1,100 148 149

Mean1 is the simple arithmetic average of all detected results (n=84) Mean2 uses the average result for each pair of field duplicate samples at 6 plants (n=78)

Summary Data (cont.)

Analyte Count

Concentration (µg/kg, dry weight)

Minimum Maximum Mean1 Mean2

BDE-138 56 1.9 40 10 8

BDE-153 84 9.1 410 69 68

BDE-154 84 7.7 440 59 58

BDE-183 84 2.1 120 16 14

BDE-209 83 215 14,500 1,737 1,617

% solids 0.3 93.2 26 26Mean1 is the simple arithmetic average of all detected results (n=84) Mean2 uses the average result for each pair of field duplicate samples at 6 plants (n=78)

Percentile Concentrations

Analyte

Percentile Concentration (µg/kg, dry weight)

99th 98th 95th 90th 50th

BDE-028 56 45 33 25 9

BDE-047 2,650 2,212 1,689 1,329 570

BDE-066 68 56 41 32 12

BDE-085 104 87 66 52 23

BDE-099 2,697 2,248 1,713 1,346 575

BDE-100 578 479 362 283 118

Percentile Concentrations

Analyte

Percentile Concentration (µg/kg, dry weight)

99th 98th 95th 90th 50th

BDE-138 35 29 21 17 7

BDE-153 265 220 166 130 54

BDE-154 231 191 144 112 46

BDE-183 60 49 37 28 11

BDE-209 7,515 6,043 4,364 3,269 1,178

BDE-138 only reported in 56 samples, BDE-209 only reported in 77 samples, all others reported in all 78 samples

Preliminary Data Analyses• Examined correlations between pairs of

congeners and with % solids and performed an analysis of variance (ANOVA) with the flow stratum

• No strong correlations with % solids for any congener (r values range from -0.22 to-0.10)

• No apparent effects of flow stratum

BDE-209 by Stratum

5.0

6.0

7.0

8.0

9.0

10.0

1 2 3

Flow Stratum

PB

DE

209 (

Log u

g/k

g)

Preliminary Analyses (cont.)

• Good correlations between congeners within the same level of bromination – All r values >0.9– Except for those involving BDE 138, for which

there were more non-detects

• Correlations between congeners in adjacent levels of bromination are lower, with r values generally between 0.8 and 0.9 for the tri- through hexa-BDEs  

Preliminary Analyses (cont.)

• Correlations between hexa and either hepta or deca congeners are much lower( r values range from 0.57 to 0.64)

• Correlation of hepta and deca congeners is only 0.67

• Deca is not well correlated with any other congeners (r values range from 0.46 to 0.67)

• Deca results similar across strata

Example Correlation Plot

100

1000

10000

100000

1 10 100 1000

PBDE 183 (ug/kg)

PB

DE

209 (

ug/k

g)

Stratum

123

Possible Implications

• Different sources for the congeners

• BDE-209 may be coming from a separate source

• Results may reflect changes in flame retardant formulations over time, mediated by human body burdens and excretion rates

Contacts• For questions about this presentation, contact:

Harry McCartyComputer Sciences Corporation703-461-2392hmccarty@csc.com

• For questions about the 2006 - 2007 Targeted National Sewage Sludge Survey, contact:

Rick StevensUSEPA National Biosolids Coordinator202-566-1135stevens.rick@epa.gov