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Exposure Assessment Methodologies:Exposure Assessment Methodologies:The Focus on Dose The Focus on Dose

Schirrmeister Diaz-Arrastia Brem, L.L.P.Pennzoil Place – North Tower700 Milam Houston, Texas 77002713.221.2500www.sdablaw.comacs @ sdablaw.com

Andrew Schirrmeister

Harris Martin Benzene Litigation ConferenceJune 2-3, 2008

New Orleans, Louisiana

Exposure Assessment Methodologies

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Dose Makes the PoisonDose Makes the Poison


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Dose: The Cornerstone of CausationDose: The Cornerstone of CausationParacelsus (1567) stated: “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy.”Threshold -- dose below which a given effect not observedExamples

AspirinOne aspirin prevents heart attacksTwo aspirins cure a headache100 aspirins can be lethal

WaterWater is necessary to life17-20 liters of water consumed in a short timeframe is lethal


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Cumulative Benzene ExposureCumulative Benzene Exposure

There is a threshold of cumulative lifetime exposure to benzene below which there is no risk of leukemiaWhat is the threshold?Studies demonstrate that exposure to benzene at less than 40 ppm-years does not cause AML

OSHAInfante/Rinsky (’87) (US Rubber Workers)Gunn (’06) (Australian Petroleum Industry)Wong (’87, ’95) (US Refinery Workers)Rushton (’97) (UK Petroleum Marketing & Distribution)Swaen (’05) (Dutch Chemical Plant)


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Cumulative Benzene ExposureCumulative Benzene Exposure“The relevant medical-scientific literature supports the conclusion that cumulative benzene exposure, at levels above 200 ppm years, can result in [AML].”

Castellow v. Chevron USA, 97 F. Supp. 2d 780, 782 (S.D. Tex. 2000)

“Consensus among scientists that a threshold of 100 ppm-years will cause leukemogenesis, scientists disagree over the effects of doses between 25 and 50 ppm-years”

Sutera v. The Perrier Group of America, Inc., 986 F. Supp. 655 (D. Mass. 1997)

“Dr. Paustenbach states in his report that the cumulative benzene exposure below which there is no increased risk of AML is between 50 and 400 ppm-years.”

Leblanc v. Chevron USA, Inc., 513 F. Supp.2d 641 (E.D. La. 2007)


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Cumulative Benzene ExposureCumulative Benzene ExposureFrank Gardner, M.D.

Threshold level of benzene exposure before AML can develop of 30-40 ppm years

Deposition of Frank Gardner, July 26, 2002

John Dement, Ph.D.“40 ppm years, probably in any one study, may have been the lowest where it showed a statistically significant excess [of AML].”

Deposition of John Dement, July 31, 2002


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Courts Are RequiringCourts Are RequiringAccurate Dose AssessmentsAccurate Dose Assessments


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FerebeeFerebee v. Chevron Chemical Co.v. Chevron Chemical Co.Requires legal sufficiency not scientific certainty

“A cause-effect relationship need not be clearly established by animal orepidemiological studies before a doctor can testify that, in his opinion, such a relationship exists. As long as the basic methodology employed to reach such a conclusion is sound, such as use of tissue samples, standard tests, and patient examination, products liability law does not preclude recovery until a ‘statistically significant’ number of people have been injured or until science has had the time and resources to complete sophisticated laboratory studies of the chemical”

Rejected evidence of insufficient exposure from defense expertTestimony was amount to cause acute, not chronic effectsJury could believe there was sufficient exposureDose-response relationship at low levels for toxic chemicals is highly debated

Case distinguishable as involving chemical with little research conductedCase pre-dates Daubert and its state-court counterpart decisions

736 F.2d 1529 (D.C. Cir. 1984)


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LohrmannLohrmann v. Pittsburg Corning Corp.v. Pittsburg Corning Corp.Regularity, frequency, proximity test

“To support a reasonable inference of substantial causation from circumstantial evidence, there must be evidence of exposure to a specific product on a regular basis over some extended period of time in proximity to where plaintiff actually worked.”

Mere evidence that product was on site insufficient

Evidence of casual or minimum contact insufficient782 F.2d 1156 (4th Cir. 1986)


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ChaversChavers v. General Motorsv. General MotorsRegularity, frequency, and proximity test

(1) “[plaintiff] was exposed to particular … product made by [defendants],(2) with sufficient frequency and regularity(3) in proximity to where he actually worked(4) such that it is probable that the exposure to [defendants’] products caused [plaintiff’s] injuries”

Levels that are harmfulThere must be evidence from which the fact-finder can conclude that the plaintiff was exposed to levels of that agent that are known to cause the kind of harm the plaintiff claims to have suffered.”

Applied to trace benzene in Roach v. PPG, 2004 WL 2239806 (Ark. App. 2004)

79 S.W.3d 361 (Ark. 2002)


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Donaldson v. Central Ill. Pub. ServiceDonaldson v. Central Ill. Pub. ServiceQuantification not required as exclusive method

“A plaintiff must establish … contact with chemicals produced by defendant. …Illinois law does not require that plaintiffs quantify the level of exposure.”

Applied strict Frye analysis, did not assess reliabilityRecord was replete with evidence tending to support causation

Multiple children in close proximity with same rare disease (epidemiologist opined probability of 1 in 10,000 that these were random)Extensive record of exposure (air-monitoring logs, health and safety diaries, soil sample analyses, odor reports, EPA reports, Department of Health reports, clean-up operations reports, environmental consultant reports, and a case report of toxic exposure)

Presently of questionable authorityNon-occupational case which does not apply frequency, proximity, regularity testIllinois adopted new standard for review of Frye decisions

767 N.E.2d 314 (Ill. 2002)


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MerrellMerrell--Dow Pharmaceuticals v. Dow Pharmaceuticals v. HavnerHavner

Statistically significant doubling of the risk Multiple studies among different groupsProof injured person was exposed to the same substanceExposure or dose levels were equal to or greater than dose in studiesExposure occurred before onset of injuryTiming of onset of injury consistent with those in the studies

953 S.W.2d 706 (Tex. 1997)


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FriasFrias v. Atlantic Richfieldv. Atlantic Richfield

Requires specific exposure assessmentFollows Havner on dose requirementsProof of causation based on specific doseScientifically reliable evidence of dose (exposure level and period of exposure) necessary to cause the diseaseLegally sufficient evidence plaintiff was exposed to that dose (at that level for that period)

104 S.W.3d 925 (Tex. App.–Hous. [14th Dist.] 2003, no writ)


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FriasFrias v. Atlantic Richfieldv. Atlantic RichfieldAbstract and indefinite exposure assessment legally insufficient:

“‘frequent contact’ with and ‘regular use’ of benzene containing products, ‘significant vapor hazard,’ and ‘dangerously high’ levels of benzene”“consistently exposed to benzene levels in the 10 to 20 ppm range … and that he had regular exposures above 100 ppm … . Occasional peak exposures of hundreds of ppm and, in some cases, approaching 1000 ppm”

“such indefinite terms as ‘consistently,’ ‘regular,’ and ‘occasional’leave the frequency (i.e., hourly, daily, weekly, monthly, etc.) and duration (minutes, hours) of exposure, at any single exposure level and in total, subject to wide variance and thus largely open to speculation”

104 S.W.3d 925 (Tex. App.–Hous. [14th Dist.] 2003, no writ)


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CastellowCastellow v. Chevron USAv. Chevron USARelevant Literature Establishes Exposure for Causation

Exposure above 200 ppm-years can cause AML

Industrial Hygienist Assessment UnreliableKept revising assessment from 177 to 104 to 61 ppm years

One assessment of benzene exposure could only occur from potentially lethal gasoline exposure twice daily for 10 years

Assessment made on assumptions unsupported in the record

Unreliable assessment leads to speculative causal link97 F.Supp.2d 780 (S. D. Tex. 2000)


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Parker v. Mobil Oil Corp.

Proof of sufficient exposure necessary“It is well-established that an opinion on causation should set forth a plaintiff’s exposure to a toxin, that the toxin is capable of causing the particular illness (general causation) and that plaintiff was exposed to sufficient levels of the toxin to cause the illness (specific causation).”

Precise quantification not always required“It is not always necessary for a plaintiff to quantify exposure levels precisely or use the dose-response relationship, provided that whatever methods an expert uses to establish causation are generally accepted in the scientific community.”

Alternate methods may be used if scientifically reliableIntensity of exposure to benzene may be more important than a cumulative dose for determining the risk of developing leukemiaExposure can be estimated through the use of mathematical modelingComparison to the exposure levels of subjects of other studies could be helpful provided that the expert made a specific comparison sufficient to show how the plaintiff's exposure level related to those of the other subjects

857 N.E.2d 1114 (N.Y. 2006)


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Parker v. Mobil Oil Corp.Requires more than conclusory assertions

“General, subjective and conclusory assertion . . . that Parker had ‘far more exposure to benzene than did the refinery workers in the epidemiological studies’ is plainly insufficient to establish causation. It neither states the level of the refinery workers’ exposure, nor specifies how Parker's exposure exceeded it, thus lacking in epidemiologic evidence to support the claim.”“Parker was ‘frequently’ exposed to ‘excessive’ amounts of gasoline and had “extensive exposures ... in both liquid and vapor form,” which-even given that an expert is not required to pinpoint exposure with complete precision-cannot be characterized as a scientific expression of Parker's exposure level.”Rejected no threshold position - “the scientific reliability of that methodology has flatly been rejected as merely a hypothesis”

857 N.E.2d 1114 (N.Y. 2006)


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Nawrocki v. Coastal Corp.Required showing of levels necessary to cause the disease“‘[A]n opinion on causation should set forth a plaintiff's exposure to a toxin, that the toxin is capable of causing the particular illness (general causation) and that plaintiff was exposed to sufficient levels of the toxin to cause the illness (specific causation).’”“The affidavit of plaintiff’s expert failed to set forth the manner in which he estimated plaintiff’s exposure to a specific level of benzene. Moreover, the affidavit of plaintiff’s expert failed to refer to any study establishing that plaintiff was exposed to sufficient levels of benzene to cause aplastic anemia.”

845 N.Y.S.2d 896 (N.Y.A.D. 2007)


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BorgBorg--Warner v. FloresWarner v. FloresSpecific Causation Requirements

Plaintiff must produce evidence of “dose” in toxic tort casesPlaintiff must produce dose evidence for individual defendantsFact finder must evaluate

Plaintiff’s quantity of toxic exposureWhether that quantity was a substantial factor in causing plaintiff’s illness“Some” exposure insufficient

“Substantial factor” measured against literature as required by HavnerStatistically significant doubling of the riskMultiple studies among differing populationsPlaintiff’s dose similar to dose in the studies

232 S.W.3d 765 (Tex. 2007)


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BorgBorg--Warner v. FloresWarner v. FloresSample interrogatory:

For each Defendant listed in Plaintiffs’ Petition, please provide:

a. The approximate dose of each product manufactured or sold by each Defendant to which Plaintiff was exposed that is alleged to have caused harm to Plaintiff;

b. The methodology used to calculate the dose; andc. Evidence that the dose was a substantial factor in causing

the harm to Plaintiff.


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Dose Methodologies


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Dose MethodologiesDose Methodologies

Actual Measurement

Proxies for Actual MeasurementOdor in the Ditch

Kopstein Reference

Literature ComparisonPublished Studies

Government Studies

Anecdotal


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Odor in the Ditch Methodology


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Odor in the DitchOdor in the Ditch

Methodology based upon perception of odor

Two types of physical reactionsSense of smell

Physical symptomsHeadache, Nausea, Dizziness, Light-headedness, Watery Eyes, Dry or Cracked Skin, Odors on body, clothing, and breath

Determine published value for these physical reactions


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Odor in the DitchOdor in the DitchMark Nicas, Ph.D., MPH, CIH

Professor – U. Cal. BerkeleyPlaintiff worked in a ditch with soil saturated with gasolineThe odors from the gasoline caused plaintiff headaches and nauseaLook to literature to determine the levels at which it is reported that people get a headache from working around gasoline Based upon the number of parts per million that has been reported to give people headaches from gasoline, and knowing how much benzene is a component of gasoline; plaintiff’s exposure to benzene can be calculated from these numbers


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Odor by Sense of SmellOdor by Sense of SmellPeter Infante, Dr.P.H., D.D.S.

Former OSHA

Based on Published Odor ThresholdsNeed to know percentage of benzene contentExample – Based on Odor of Gasoline

Odor threshold for gasoline is 140 ppmBenzene content of gasoline is 1%Benzene exposure is approx. 1.4 ppm (1% of 140 ppm)

Deposition of Peter Infante, January 10, 2005


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InaccuraciesInaccuraciesInaccuracies in Assessment by Odor ThresholdsInaccuracies in Assessment by Odor ThresholdsMultiple substances typically found in work place

Difficult to discriminate and distinguish odors

Workers not trained to recognize specific odors

Misconceptions and erroneous information on odors

Odor threshold subject to large individual variation

Odor threshold subject to desensitization


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Published Odor ThresholdsPublished Odor ThresholdsOdor ThresholdsOdor ThresholdsSource: NOAA Office of Response and RestorationGreat Variations

Toluene threshold varies >400%Xylene threshold varies >100%Benzene threshold varies >400%


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Published Odor ThresholdsPublished Odor ThresholdsOdor ThresholdsOdor ThresholdsAmerican Industrial Hygiene AssociationOdor threshold data reported in the literature differ considerably. It is not uncommon for reported threshold values to range over four orders of magnitude for the same chemical.


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Inability to DifferentiateInability to DifferentiateOpiekun, RE, et al, “A Controlled Short-term Exposure Study to Investigate the Odor Difference Among Three Different Formulations of Gasoline”

Chem. Senses 25:395-400, 2000

Study performed on various formulations of gasoline

GasolineGasoline + MTBEGasoline + MTBE + Reodorant

Study subjects unable to distinguish among the odor of the three formulations


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Kopstein Reference Methodology


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PlaintiffsPlaintiffs’’ ExpertExpert2006 Melvyn 2006 Melvyn KopsteinKopstein

Potential Uses of Petrochemical Products Can Result in Significant Benzene Exposures: MSDS Must List Benzene as an Ingredient; Journal of Occupational and Environmental Hygiene, 3: 1-8 Amount of benzene in commonly used solvents has remained unchanged since 1955Provides benzene content of petrochemicals, most range from 0.1% to 7%Peer-reviewed article provides basis for greatly exaggerated exposure assessments in benzene litigation


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Plaintiffs Article on Benzene ContentPlaintiffs Article on Benzene ContentMelvyn Kopstein’s articleBenzene content of solvents

Toluene – up to 1%Naphtha – greater than 1%n-Hexane – up to 6%Alkyd paint – up to 1%32 Naphtha solvents – up to 7%

These values in a peer-reviewed article provided evidentiary basis for grossly-exaggerated exposure assessments


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KopsteinKopstein Article MethodologyArticle MethodologyCalculate inhalation exposure based upon benzene content reported in Dr. Kopstein’s article

Estimate benzene content in solvents that plaintiff worked with based upon Dr. Kopstein’s articleEstimate time plaintiff worked with products performing different tasks over his work lifeCalculate an inhalation amount of benzene

Calculate similar dermal exposure number based upon benzene content reported in Dr. Kopstein’s article

Perform similar calculationsConvert weight of dermally absorbed benzene to equivalent inhalation ppm

Add together for cumulative part per million year exposure assessment


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InaccuraciesInaccuraciesInaccuracies in Inaccuracies in KopsteinKopstein’’ss ArticleArticle

Does not rely on manufacturer’s actual data and raw material specificationsKopstein article assumes high benzene content based on 1950s dataKopstein article assumes high benzene content based on industrial grades of solvents and does not account for higher quality solvents used in manufactureKopstein article fails to account for changes due to regulatory changes

Benzene standard of 1977/1978HazCom standard of 1983Benzene standard of 1987

Kopstein article fails to account for individual manufacturer’s benzene reduction


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Literature Comparison Methodology


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Literature ReviewLiterature Review

Reported Industrial Hygiene Monitoring ResultsReported Industrial Hygiene Monitoring ResultsUsed when there is no actual or empirical dataOnly reliable if conditions are similarMany Pitfalls

Specific products usually not identifiedBenzene content not identifiedVentilation characteristics not identifiedMany from foreign countries with poor industrial hygiene programs and high benzene contamination in solvents


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Published Literature


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Literature DoseLiterature Dose

Frank Parker, CIH, CSPIndustrial hygienist

Literature on painter exposureAverage in articles 1 – 50 ppmExclusion of 1 study from Taiwan lowers

average to less than 1 ppm

John Dement, Ph.D.Duke University

Literature on painter exposureRange of plausible exposure 0 - 138 ppm

Range of possible or plausible exposuresRange of possible or plausible exposures


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New Hampshire Auto Dealers New Hampshire Auto Dealers AssAss’’nnNew Hampshire Auto Dealers Association, Worker Exposure to Volatile Aliphatic and Aromatic Hydrocarbons in Eight Auto body paint shops in New Hampshire, 1987Conducted in winter, doors & windows closed, general ventilation minimalLong-term personal & area monitoring21 samples collected“None of the auto paint shop atmospheres examined in this study show any evidence of benzene … contamination.”“worker exposure to volatile aliphatic and aromatic compounds are well below current OSHA threshold limit values.”


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Trace Benzene Auto Body Shop LiteratureTrace Benzene Auto Body Shop Literature

Winder and Turner, Solvent Exposure and Related Work Practices Amongst Apprentice Spray Painters in Automotive Body Repair Workshops, Ann. Occ. Hyg., 36:385-394 (1992)Long-term samples at 46 sites70 samples collectedCurrent OSHA standard = 1 ppm/8 hrsHighest = 0.3 ppmAverage = <.06 ppm67 of 70 samples NO Benzene detected


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Medinilla and Espigares, Contamination by Organic Solvents in Auto Paint Shops, Ann. Occ. Hyg., 32:509-513 (1988)Short-term samples at 11 sites11 samples collectedCurrent OSHA standard = 1 ppm/8 hrsAverage = .23 ppm8 of 11 samples no benzene detected


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Trace Benzene Auto Body Shop LiteratureTrace Benzene Auto Body Shop LiteratureChen, et al, Exposure to mixtures of solvents among paint workers and biochemical alterations of liver function, Br. J. Indus. Med., 48:696-701 (1991)Car painters in paint booths in Taiwan

9 samples, 15 min. TWABenzene – 7-138 ppm (mean 53 ppm)Toluene – 12-948 ppmXylene – 25-511 ppm

No information about benzene content of paint or solventsNo information about industrial hygiene practices or air flow characteristics

Booths described as “poorly ventilated”

U. S. standards and practices do not apply


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Jayjock and Levin, Health Hazards in a Small Automotive Body Repair Shop, Ann. Occ. Hyg., 28:19-29 (1984)5 short-term samples, lacquer

Average <1 ppmRange 0 - 1.1

13 short-term samples, enamelAverage = 2.66 ppmRange 0 - 11


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Literature ReviewLiterature ReviewOther Literature reporting benzene exposure levelsOther Literature reporting benzene exposure levels

Caldwell, et al, Hydrocarbon Solvent Exposure Data: Compilation and Analysis of the Literature, AIHAJ 61:881-894 (2000)Nelson, et al, Historical Characterization of Exposure to Mixed Solvents for an Epidemiologic Study of Automotive Assembly Plant Workers, Appl. Occup. Environ. Hyg. 8(8):693-702 (1993)Wallace, Major Sources of Benzene Exposure, Env. Health Persp., 82:165-169 (1989)


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Government Literature


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General Governmental FindingsGeneral Governmental FindingsOSHA examined benzene in its regulatory processOSHA examined benzene in its regulatory processPreamble to 1987 Benzene Standard

Record evidence indicates that liquid mixtures with less than 0.1 percent benzene are unlikely to cause exposures through dermal absorption and inhalation equivalent to the amount inhaled at the action level. [The “action level” was an eight hour time weighted average airborne concentration of 0.5 ppm. 29 C.F.R. § 1910.1028(a)(3)(b).]

Federal Register: Occupational Exposure to Benzene, Final Rule, 52 F.R. 34460, 34461 (September 11, 1987)


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Specific Government InvestigationSpecific Government Investigation

NIOSH, “An Evaluation of Engineering Control Technology for Spray Painting”

1 site

Long-term Samples

Lacquer paint used

No benzene detected


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OSHA InspectionsOSHA InspectionsIndustrial hygiene inspections conducted by Federal and State OSHA in auto body repair shops throughout the United StatesGeographically dispersed, long-term personal samples8 sites12 samplesCurrent OSHA standard = 1 ppm/8 hrsAverage = <1 ppm (lacquer)3 of 12 samples = <.014 ppmLong-term area sample = .088 ppm8 of 12 samples No Benzene detected


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Literature ReviewLiterature ReviewOther Government Literature reporting benzene Other Government Literature reporting benzene exposure levelsexposure levelsNIOSH Health Hazard Evaluation Report: HETA #2002-0418-2912, Richards Industries, Cincinnati, Ohio, September 2003NIOSH Health Hazard Evaluation Report: HETA 91-0341-2380, Bryan Custom Plastics, Bryan, Ohio, January 1994OSHA Inspection Number 102475225, Superior Auto Body, Inc., Eau Claire, Wisconsin, October 1991


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Anecdotal Methodology


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AnecdotalAnecdotal

Unsubstantiated reports of general workplace practices

Odor in the air

Odors on body, clothing, and breath

Dry and cracked skin

Headache, Nausea, Dizziness, Light-headedness, Watery Eyes

Mere presence around substance


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AnecdotalAnecdotalPremises ConditionsPremises Conditions

“The story I heard from him is not different from the stories I've heard from a lot of other workers that used benzene or gasoline to clean their tools, clean their hands.”

Deposition of Peter Infante, January 11, 1999

They said you could always smell benzene in the styrene area. If you could always smell benzene in the styrene area, the exposures, one would estimate them to be between 60 and 90 parts per million.

Deposition of Peter Infante, April 23, 2001


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AnecdotalAnecdotalMixing PaintMixing Paint

A. The odors are very strong up by the counter. So that's a clear indication that ventilation was poor, and that there was a large amount of volatiles present in that space.

Q. Based upon the presence of odors and little, if any, ventilation you conclude that the TLV for ten parts per million was exceeded?

A. Could be exceeded while mixing paint.Deposition of Stephen E. Petty, November 21, 2003


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AnecdotalAnecdotalMere use of productsMere use of products

“It was known to the manufacturers that paint product mixing practices, parts cleaning practices, and service station attendant gasoline usage practices were not protective of human health as recognized by good industrial hygiene practice.”

Deposition of Stephen E. Petty, November 21, 2003


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AnecdotalAnecdotalI have formed the following opinions:

1. Plaintiff worked with and was exposed to benzene containing solvents substantially daily starting in 1972 until he quit work for medical reasons in approximately 2002.

2. He was exposed both by inhalation and skin absorption.

3. Plaintiff had a significant benzene exposure every time he used benzene containing materials.

4. Skin contact with these solvents would have significantly contributed to his overall dose of benzene.

Expert report of Frank M. Parker, May 28, 2007


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Fact of ExposureFact of ExposureDr. Gregory Oakhill, M.D.

Board Certified DoctorNot Industrial Hygienist

“It is my opinion that plaintiff’s twenty plus year exposure to benzene containing products contributed to cause his AML.”“I don’t know of a sufficient amount to cause AML. . . . he was exposed to something that is known to cause AML, and he was exposed to it over a two-decade period of time. That, in my medical opinion, gives it significant weight that I think I can make that opinion.”Excluded as to causation – affirmed by court of Appeals – “Dr. Oakhill’s testimony did not meet the Chavers requirements when he stated that he did not know of any threshold limit of exposure to benzene, nor did he need to know the level of decedent’s exposure to benzene in order to form his opinion.”


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Example of CompetingExposure Assessments


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Exposure AssessmentsExposure AssessmentsMark Nicas, Ph.D., MPH, CIH

Professor – U Cal Berkeley

Performed exposure assessmentPlaintiff exposed to 67.5 ppm-yr benzene

Bradford A. Russell, MS, CIH, CPEAFormer OSHA and EPA

Based on same dataPlaintiff exposed to 0.306 ppm-yr benzene


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PlaintiffPlaintiff’’s Exposure Assessments Exposure AssessmentMark Nicas, Ph.D., MPH, CIHPlaintiff was painter, painter’s helper, and body man

Identify all tasks and total time performing each taskEstimated time manually wiping with solvent \was 1,575 hours, or: (462 days) x (3 hours/day) + (189 days) x (1 hours/day) = 1,575 hours

Identify all solvents for each tasks and time of usageAssume plaintiff split 95% of cleaning time equally among three solvents, including enamel reducer

Determine benzene content of solventBased on formula and Kopstein’s article, enamel reducer contained 0.5% benzene. One gallon (3,785 mL) of enamel reducer (density 795 mg/mL) had an estimated benzene content of 0.5% wt/wt, which corresponds to 15,045 mg benzene, or: (3,785 mL) x (795 mg/mL) x (0.005) = 15,045 mg.Benzene content for each solvent based on midpoint values reported in Kopstein’s article


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PlaintiffPlaintiff’’s Exposure Assessments Exposure AssessmentDermal absorption

Look to literature to identify rate of dermal absorptionIn vitro studies – 0.25 to 1.85 mg/cm2-hrIn vivo study – 0.37 mg/cm2-hrPlaintiff had cracked skin which increases absorption 5 foldUsing in vivo study x 5 gives absorption rate of 1.85 mg/cm2-hrDermal absorption can be converted to ppm-yrs

1 ppm-yr = 3,062 mg absorbed benzene

Identify area of plaintiff’s skin that was exposed to solventOne entire hand, palm of other hand, half of forearm both sides

According to literature – 915 cm2

Absorbed benzene dose:(1/3) x 0.95 x (1,575 hours) x (915 cm2) x (0.0093 mg/cm2-hr) = 4,240 mg


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PlaintiffPlaintiff’’s Exposure Assessments Exposure AssessmentInhalation exposure

1,575 hours wiping solventsEach cleaning 20 minutes using ½ quart of solvent

½ quart enamel reducer contained 1,881 mg benzeneBenzene emission rate was 94.1 mg/minAssumed breathing zone in hemispherical near field zone with radius r =3.0 ft. Assumed random air speed S = 12 ft/min), such that β = ½ x (2 π r2) x S = ½ x (2 π 32) x 12 =339 ft3/min = 9.61 m3/min. Assuming a steady-state concentration in the near field zone and β= 9.61 m3/min, the steady state exposure concentration due to direct evaporation into the near field zone was: CSS = G mg/min / 9.61 m3 /min

CSS = 94.1 mg/min / 9.61 m3 /min = 9.79 mg/m3 = 3.07 ppmCumulative benzene inhalation = 0.316 x (3,133 hr + 1,575 hr) x (3.07 ppm) = 4,567 ppm-hours


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PlaintiffPlaintiff’’s Exposure Assessments Exposure AssessmentRepeat the analysis for each task and sum upDermal absorption = 38.18 ppm-yrInhalation exposure = 29.28 ppm-yr

Total exposure = 67.5 ppm-yr


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DefendantDefendant’’s Exposure Assessments Exposure AssessmentBradford A. Russell, MS, CIH, CPEAAdjusted times performing tasks for reality

Plaintiff listed tasks and times that totaled over 26 hours for 12 hour workday

Used analytical data of benzene content provided by manufacturerrather than reliance on highly variable secondary sourcesAssumed all potential trace benzene evaporated into air, eliminating need for separate dermal calculation

If all benzene evaporates (in Nicas calculations) what is left dermally?Considered ventilation and respiratory protectionsLiterature from published studies, government studies, and manufacturer’s studies confirmed low levels of exposure

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