Lisa J. Yost, M.P.H., DABT

Ms. Yost is a board-certified toxicologist with expertise in evaluating human health risks associated with substances in soil, water, and the food chain. She has conducted or supervised risk assessments under CERCLA, RCRA, or state-led regulatory contexts involving a wide range of chemicals and exposure situations. Ms. Yost assists clients in negotiating with regulatory agency representatives or other parties to resolve issues related to human exposure to toxic substances. She seeks to develop and apply sound technical approaches that realistically characterize potential risk and meet clients’ environmental and business objectives. Her particular areas of specialization include exposure and risk assessment, risk communication, and the toxicology of chemicals such as PCDDs and PCDFs, PCBs, pentachlorophenol (PCP), trichloroethylene (TCE), mercury, and arsenic. She has also conducted reviews of the relative potential for a wide range of chemicals carried in commerce to result in acute or chronic toxicity.

Ms. Yost assists clients in identifying strategic approaches to human health issues and stakeholder concerns in the process of remediation and redevelopment of affected properties. She has provided and directed preparation of detailed technical comments on regulations regarding risk assessment methods as they affect remedial decisions and on the interpretation of toxicological literature within regulatory documents. She assists in developing remedial decision frameworks to facilitate a sound and predictable approach to site remediation. She has identified variables in risk assessment of PCBs that most affect remedial decisions and collaborated in original research on key issues affecting risk assessments for arsenic in soil or in the food chain. Ms. Yost has also had extensive involvement in risk communication and strategy development in addressing concerns related to workplace exposure to TCE in drinking water.

Ms. Yost has extensive experience in providing scientific support for litigation. This includes research and evaluations in toxicology on occupational and environmental health issues related to a variety of toxic substances, including PCBs, TCDD, PCP, 2,4,5-T, arsenic, TCE, formaldehyde, and respiratory toxins including asbestos. Ms. Yost has prepared scientific issue papers and chronologies; analyzed expert depositions for accuracy; and co-authored materials for seminars on the toxic effects of PCBs, TCDD, PCP, and aromatic amines for attorneys and scientific experts.

Tsuji JS, Yost LJ, Barraj LM, Scrafford CG, Mink PJ. Use of background inorganic arsenic exposures to provide perspective on risk assessment results. Regul Toxicol Pharmacol 2007; 48:59–68.

Mandel JH, Kelsh MA, Mink PJ, Alexander DD, Kalmes RM, Weingart M, Yost L, Goodman M. Occupational trichloroethylene exposure and non-Hodgkin’s lymphoma: A meta-analysis and review. Occup Environ Med 2006; 63:597–607; originally published online 27 Apr 2006.

Yost LJ, Tao S-H, Egan SK, Barraj LM, Smith KM, Tsuji JS, Lowney YW, Schoof RA, Rachman NJ. Estimation of dietary intake of inorganic arsenic in U.S. children. Hum Ecol Risk Assess 2004; 10:473-483.

Yost LJ, Shock S, Garry M, Garson YN, Sugino AK, Shields WJ. Health risk evaluation of PCBs from joint compound measured on surfaces and in air. Organohal Comp 2003; 63:413-416.

Meacher DM, Menzel DB, Dillencourt, M.D., et al. Estimation of multimedia inorganic arsenic intake in the U.S. population. Hum Ecol Risk Assess 2002; 8(7):1697-721

Peek DC, Butcher MK, Shields WJ, Yost LJ, Maloy JA. Discrimination of aerial deposition sources of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran downwind from a pulp mill near Ketchikan, Alaska. Environ Sci Technol 2002; 36(8):1671-1675

Yost LJ, Shields WJ, Peek DC, Schoof RA, Ruby MV, Maloy JA. Identification and hazard evaluation of crushed rock as an unexpected source of elevated arsenic in soil. Poster presented at the Society for Environmental Geochemistry and Health’s Fourth International Conference on Arsenic Exposure and Health Effects, San Diego, CA, July 2000.

Moore M, Maloy J, Yost LJ, Shields W, Petito Boyce C. Exposure to PCDDs/Fs: Relative importance of the diet and of soil. TAPPI International Environmental Conference, Volume 3, pp. 1103–1112, TAPPI Press, Atlanta, GA, 1999.

Schoof RA, Yost LJ, Eickhoff J, Crecelius EA, Cragin DW, Meacher DM, Menzel DB. A market basket survey of inorganic arsenic in food. Food Chem Toxicol 1999; 37(8):839–846.

Schoof RA, Eickhoff J, Yost LJ, Crecelius EA, Cragin DW, Meacher DM, Menzel DB. Dietary exposure to inorganic arsenic. Proceedings, 3rd International Conference on Arsenic Exposure and Health Effects, pp. 81–88, Elsevier Science Ltd., 1999.

Shields W, Maloy JA, Yost L, Peek D. Comparison of soil concentrations of dioxins and furans with predictions based on aerial deposition modeling. pp. 455–458. In: Organohalogen Compounds, Volume 41. Mocarelli P (ed), University of Milano-Bicocca. Dioxin ‘99, 19th International Symposium on Halogenated Environmental Organic Pollutants and POPs, Venice, Italy, September 12–17, 1999.

Shields WJ., Maloy JA, Winges K, Richmond K, Yost L, Peek D. Aerial deposition of dioxins and furans from a dissolving sulfite pulp mill in southeast Alaska. TAPPI International Environmental Conference, Volume 3, pp. 1071–1084,TAPPI Press, Atlanta, GA, 1999.

Yost LJ, Maloy J, Gard N, Moore M, Shields W, Jacobs L. Dioxins: Threat versus reality. A case study at a sulfite pulp mill. TAPPI International Environmental Conference, Volume 3, pp. 1085–1102, TAPPI Press, Atlanta, GA, 1999.

Schoof RA, Yost LJ, Crecelius E, Irgolic K, Guo H-R, Greene HL. Dietary arsenic intake in Taiwanese districts with elevated arsenic in drinking water. Hum Ecol Risk Assess 1998; 4(1):117–135.

Yost LJ, Schoof RA, Aucoin R. Intake of inorganic arsenic in the North American diet. Hum Ecol Risk Assess 1998; 4(1).

Slayton TM, Beck BD, Reynolds KA, Chapnick SD, Valberg PA, Yost LJ, Schoof RA, Gauthier TD, Jones L. Issues in arsenic cancer risk assessment. Environ Health Perspect 1996; 104(10):1012–1013.

Yost LJ, Schoof RA. Risk estimates for consumption of seafood collected near the proposed Kensington Mine outfall. Proceedings, 2nd Annual Conference on Arsenic Exposure and Health Effects, San Diego, CA, 1995.

Bergstrom PD, Greene HL, Schoof RA, Petito Boyce C, Yost LJ, Beck BD, Valberg PA. The use of site-specific studies to assess arsenic health risk at a Superfund site. Arsenic: Exposure and health. St. Lucie Press, Delray Beach, FL, 1995.

Karch NJ, Golden RJ, Lowenbach WA, Yost LJ, Weiss AL. Identification and ranking of chemical hazards for the railroad industry. J Am Coll Toxicol 1987; 6(2):171–184.

Published Abstracts

Kaetzel RS, Yost LJ, O’Boyle RA, Shirley CH, Booth PN. Predictive human health risk assessment for a new aluminum smelter in Iceland. Poster at the 46th Society of Toxicology Annual Meeting, Charlotte, NC, March 27, 2007.

Yost LJ, Shock SS, Noggle JJ. Lack of complete exposure pathways for metals in natural and FGD gypsum. Poster at Society of Environmental Toxicology and Chemistry Annual Meeting Milwaukee, WI, 2007.

Noggle JJ, Shock SS, Bloom N, Yost LJ. Evaluation of potential for mercury volatilization from gypsum products using flux chamber tests. Poster at Society of Environmental Toxicology and Chemistry Annual Meeting, Milwaukee, WI, 2007.

Yost L, Tsuji JS, Scrafford CG, Barraj LM, Mink PJ. Implications of changes in arsenic cancer slope factor for risk communication. Toxicologist 2006; 90(1), Abstract 2180.

Yost L, Greene JF, Hays SM, Kelsh M, Li A, Sheehan P. Derivation of range of interim inhalation cancer slope factors for TCE using physiologically based pharmacokinetic modeling, 2004.

Garry MR, Yost LJ, Shock S, Shields WJ. Assessment of metals exposure associated with subsistence use of caribou collected near a mining transport road in northwest Alaska. Poster presentation at the 43rd Annual Meeting of the Society of Toxicology, Baltimore, MD, March 21-25, 2004.

Yost L, Greene JF, Hays SM, Kelsh M, Li A, Sheehan P. Derivation of a range of interim inhalation cancer slope factors for TCE using physiologically based pharmacokinetic modeling. Poster presentation at the 43rd Annual Meeting of the Society of Toxicology, Baltimore, MD, March 21-25, 2004.

Yost LJ, Schoof RA, Garry MR. Estimation of dietary intake of inorganic arsenic in children. Poster presentation at the 40th Annual Meeting of the Society of Toxicology, Nashville, TN, March 18-21, 2002.

Schoof RA, Yost LJ. Estimation of inorganic arsenic intake in fish: Market basket vs. recreational catches. Poster presentation at the 40th Annual Meeting of the Society of Toxicology, Nashville, TN, March 18-21, 2002.

Schoof RA, Yost LJ. A market basket survey of inorganic arsenic in food. p. 13. In: 3rd International Conference on Arsenic Exposure and Health Effects, Book of Abstracts, San Diego, CA, July 12–15, 1998.

Schoof RA, Yost LJ, Beck B, Valberg P. Recalculation of the oral arsenic reference dose and cancer slope factor using revised assumptions of inorganic arsenic intake from food. Toxicologist 1993; 14(1) Abstract 51:36.

Yost LJ, Sexton JE, Pastorok RA. PCDD and PCDF concentrations in Puget Sound crabs. Toxicologist 1992; 12(1) Abstract 1167:302.

Presentations

Tsuji JS, Yost L, Barraj L. Background inorganic arsenic exposures in children. Session on CCA Treated Wood—Regulations, Science, and Risk Assessment. The Annual International Conference on Soils Sediments and Water, University of Massachusetts, Amherst, MA, October 22, 2003.

Yost L, Tsuji JS, Scrafford CG, Barraj LM, Mink PJ. Implications of changes in the arsenic cancer slope factor for risk communication. Society of Toxicology Annual Meeting. San Diego, CA, 2005.

Yost LJ. Conceptual site model: A tool for expedited redevelopment. Presented at the Association for Environmental Health of Soils, San Diego, CA. March 20, 2002.

Yost LJ, McCrone L. Sediment risk assessment: Methods and issues. Presentation at Washington Mutual, Ogden, Murphy, Wallace, and AIG Consultants, Inc. Seattle, WA, December 11, 2001.

Yost LJ. Issues in risk assessment for mercury. Presented at the 16th International Conference on Contaminated Soils, Sediments, and Water, Amherst, MA, October 18, 2000.

Yost LJ, Shields WJ, Folwarko S. Dioxins and furans background, toxicity, and issues in sediments. Presented to Western States Petroleum Association, at an annual technical seminar for WSPA members and state regulators, 1999.

Yost LJ, Schoof RA. Implications of the methylation status of arsenic in homegrown vegetables for risk assessment. Presented at the Society for Environmental Geochemistry and Health International Conference on Arsenic Exposure and Health Effects, New Orleans, LA, July 28, 1993.

Yost LJ, Evans CG. Implications of reduced oral absorption of contaminants from soil for human health risk assessment. Presented at Society for Risk Analysis Annual Meeting, San Diego, CA, December 6–9, 1992.

Petito Boyce C, Yost LJ. Methods for evaluating risks associated with residual petroleum hydrocarbons. Presented at the Society for Risk Analysis Annual Meeting. December 9, 1992.

Yost LJ, Schoof RA, Evans CE, Nelson DM. Human health risk assessment for a former wood treatment plant. Abstract TA 4F2. 13th Annual Meeting of the Society of Environmental Toxicology and Chemistry, Cincinnati, OH, November 8–12, 1992.

• Senior Scientist, Karch & Associates, 1984-1989
• Staff Scientist, Clement and Associates, 1981-1982
• Internship Coordinator, National Women’s Health Network, 1980-1981
• Summer Intern, EPA, Office of Research and Development, 1979
  

Solvents and Petroleum Products

Project manager providing technical support for a manufacturing facility in Oregon that detected tetrachloroethylene and TCE in the well supplying water to a large workforce. Worked with Exponent epidemiological and medical experts to identify key health issues for further consideration. Negotiated with technical experts from regulatory agencies (Oregon Department of Health, Oregon Department of Environmental Quality [DEQ], and ATSDR), the Portland community (Oregon Health Sciences University), and with consulting firms and law firms to develop an appropriate means to evaluate health effects in children of female employees, both in medical monitoring and in ongoing health investigations initiated by regulatory agencies. Addressed issues and questions related to the medical monitoring or other health concerns at more than 60 meetings with former workers and in one-on-one conversations with workers who felt that their health problems might be related to exposure to chemicals in the workplace drinking water. Briefed project team on new epidemiological literature, and collaborated with the team on issues related to workers’ compensation claims and litigation strategy.

As part of a 5-year review under Superfund, the 2001 draft carcinogenic slope factors for TCE prompted additional investigations regarding indoor air. Served on a project team that prepared a weight-of-evidence analysis of the carcinogenicity data for TCE. The team selected a range of inhalation carcinogenic slope factors for application at a number of facilities under consideration because of concerns regarding migration of volatile chemicals including TCE from groundwater to indoor air.

Managed a project team of toxicologists and epidemiologists providing detailed comments on the EPA Risk Characterization Document for TCE issued in 2000. Comments were submitted seeking a more full and unbiased evaluation of the underlying data on effects of TCE with particular emphasis on the importance of dose and increased reliance on findings from available well-designed epidemiological investigations. Coordinated toxicological input into comments submitted to the National Toxicology Program regarding proposed listing of TCE as a known human carcinogen. The agency did not ultimately determine that such a reclassification was warranted and decided to maintain the current classification of “reasonably anticipated to be a carcinogen.”

Served as lead toxicologist at two sites in Oregon undergoing investigation and risk assessment under regulatory guidelines identified by the State DEQ. At both sites, conducted comprehensive exposure pathway analyses, including the evaluation of the potential for cross-media contamination, and identified limited exposure potential. One site was a former gas-manufacturing plant with residual petroleum hydrocarbons in soil and groundwater, and the second site was a former flower bulb treating facility with residual pesticides in soil. Worked with the Exponent project team in negotiating with DEQ regarding the HHRA and cleanup decisions regarding the former gas-manufacturing facility.

Led a multipathway human health risk assessment evaluating potential effects to workers related to hypothetical exposure to toluene, methyl ethyl ketone, and acetone in groundwater and soil at a manufacturing facility in southwestern Oregon. Project team was able to negotiate a reasonable means to estimate concentrations of solvents that would occur in a supply well as opposed to initial use of findings from individual low-draw wells. Assessment was part of the ultimate resolution that site solvents were contained within site boundaries and could be addressed with monitoring and natural attenuation.

Managed a project to develop risk-based cleanup levels for a former bulk fuel terminal in Seattle, Washington. Worked with a team of contractors to develop a cost-effective approach that was protective of public health and the environment. Selected approach was based on toxic constituents of petroleum hydrocarbons (i.e., benzene, toluene, ethylbenzene, xylene, and PAHs) rather than total petroleum hydrocarbons and greatly reduced areas identified as requiring cleanup. Presented the approach to risk assessment for the site at meetings with the Washington State Department of Ecology.

Provided technical support to private clients in litigation regarding exposure in occupational and environmental settings. Conducted detailed reviews of experts’ publications and depositions provided for plaintiffs in litigation regarding TCE and perchloroethylene in groundwater.

Directed literature searches on 30 chemicals found in Love Canal, and prepared profiles on the health effects of several of these substances, including TCE, 1,1 dichloroethene, and perchloroethylene, in support of litigation.

Air Toxics

Provided technical oversight, toxicological review, and risk communication support on a risk assessment conducted as part of an environmental impact statement for development of a refinery in Fjardaal, Iceland. In this context, helped to develop the risk assessment approach to apply air model estimates and evaluate all potential human health pathways related to release of PAHs, SO2 and fluoride from the plant. Assisted the client in presenting the approach to the Icelandic regulatory board and in crafting risk communication materials to be used for the public.

Managed an investigation and risk communication at a wood pulp processing facility in southwest Washington, where an accidental release of hydrogen sulfide, methyl mercaptan, and other mercaptans had resulted in temporary illness in a group of children. Assisted in developing risk communication materials and in preparation for a meeting with the representative from the Washington State Department of Health.

Conducted a human health risk assessment regarding the use of formaldehyde to sterilize storage areas in the production of a food product. Evaluated all potential exposure pathways related to this use. Issues included potential concentrations in the final product and formaldehyde in residual biomass used in feeding cattle. The use as specified was found to be well within acceptable levels as a result of high volatility of formaldehyde.

Evaluated scientific literature on the carcinogenic, respiratory, and irritant effects of formaldehyde associated with exposure to levels similar to those measured in a plaintiff’s home, in litigation involving exposure to formaldehyde in a new mobile home. Also supervised a literature search and review of immunologic effects of formaldehyde and helped develop testimony for the case.

Reviewed scientific literature on 26 respiratory toxins, conducted risk assessments on selected carcinogens, and maintained a database on more than 200 chemicals regulated under OSHA’s Air Contaminant Rule.

Collaborated in the development of a unique system to rank more than 200 toxic chemicals carried in commerce by railroad for the risk of acute lethality and serious permanent health effects related to short-term airborne releases. Assisted in preparing comments on proposed changes in DOT regulations affecting the transportation of hazardous materials by rail.

Reviewed and evaluated risks associated with airborne exposure to toxic chemicals, including lead, PCBs, and PCDDs and PCDFs expected from a municipal garbage incinerator that was planned for Essex County, New Jersey.

Reviewed the toxicologic and epidemiologic data that investigated cardiopulmonary effects of carbon black. Key issues included control of confounding factors in epidemiologic studies and evidence for a no-apparent-effects threshold in studies in experimental animals. Prepared a report that was submitted to OSHA as part of an effort by the industry to have carbon black reclassified as a nuisance dust.

Evaluated the epidemiologic and toxicologic literature on the health risks associated with the ingestion of asbestos for a public water utility in southern California. This review also investigated the weathering of asbestos fibers in water as a mechanism for the reduction in the carcinogenic potency of ingested versus inhaled asbestos.

Prepared a chronology of the state-of-the-art industrial hygiene approaches for asbestos for the time period from the turn of the century to 1988. Also directed a review of the epidemiologic literature on asbestos and mesothelioma and lung cancer, and prepared an evaluation of potential alternative causes of mesothelioma.

Prepared a case study on the health issues and the legislative and regulatory history of the use of asbestos insulation in school buildings nationwide as part of a discussion of standard setting for a utilities cooperative in Minnesota.

Metals and Mining

Managed two tasks providing technical support to a client in preparing a regional management plan/EIS for a former asbestos mine located in the central California Coast range and surrounding recreational area that contains natural deposits of chrysotile asbestos. In one task, collaborated on design of a pilot-scale study to evaluate revegetation potential for severely disturbed and naturally unvegetated portions of the site. In a second task, evaluated the cost-effectiveness, feasibility, and maintenance requirements of sediment retention structures proposed by EPA in a feasibility study for the former mine. Prepared a human health risk assessment to evaluate risks associated with inhalation of asbestos from native chrysotile sources occurring within this area. Key issues in the risk assessment were the usability of available ambient asbestos data for risk assessment, quantification of uncertainties in EPA’s unit risk factor for inhalation of asbestos, and identification of representative exposure variables for estimation of risks associated with recreational uses of the area. Successfully negotiated with representatives from EPA Region 9 to develop a cost-effective approach that was acceptable to the client and EPA.

Reviewed a risk assessment associated with a former asbestos mine that predicted excess cancer risks from exposure to asbestos in drinking water, soil, and air. The key toxicologic issues included the weight of evidence for carcinogenic effects of asbestos in water and the relevance of increased incidence of benign tumors in experimental animals to predict excess cancer risks in human populations.

Assisted in risk communication regarding potential health risks related to fugitive dust along an ore haul road and port facility in northwest Alaska. Detection of elevated metals in roadside dust in sensitive tundra habitats raised community concerns about risks from subsistence foods and adverse effects to the environment. Evaluated potential risks related to high-level consumption of berries, with site-specific concentrations of arsenic, cadmium, lead, and zinc. Provided risk estimates, discussed approach with consultant for the regulatory agency, and provided information on background exposure to arsenic in foods.

Conducted a human health risk assessment to evaluate potential effects of mercury and PCBs in sediments in an urban lake in New York State. Detailed analysis of uncertainties in EPA’s approach to risk assessment of methylmercury and selection of a representative fish consumption rate were critical issues in the risk assessment. Although the human health risk assessment assumptions required by the State resulted in risks above acceptable levels identified by the regulatory agency, actual risks appeared to be much lower based on application of more relevant mercury toxicity values from the recent literature derived from fish-eating populations.

Served on a project team providing detailed comments to EPA regarding the use of copper chromated arsenical pesticides as wood preservatives. Participated in strategy meetings identifying key issues and approaches, drafted comments for internal and client review, and coordinated research into exposure aspects of the assessment.

Evaluated the potential for arsenic to accumulate into seafood for a client considering redevelopment of property on the Duwamish River in Washington with residual arsenic in soil and groundwater. Consideration of site-specific factors, including likely species present (i.e., lack of shellfish habitat and collection areas) and the methylation status of arsenic in popularly consumed finfish, resulted in more than a 30-fold reduction in estimated concentrations of toxic forms of arsenic likely consumed by anglers relative to those derived on the basis of generic assumptions in the EPA ambient water quality criteria for arsenic.

Collaborated on an investigation of arsenic intake in the diets of people living in areas of Taiwan with elevated arsenic concentrations in artesian well water. Dietary intake of inorganic arsenic was substantially higher than assumed by EPA, suggesting that EPA’s toxicity values might overestimate arsenic toxicity. In a separate investigation for a client in litigation, assisted in the direction of a comprehensive study to estimate exposure to inorganic arsenic in the diet. Used findings to establish the relative importance of the dietary sources in comparison with environmental exposures resulting from alleged releases from the client’s facility.

Prepared a human health risk assessment in support of a permit application for reopening the A J Gold Mine near Juneau, Alaska. Risk estimates were calculated for exposure to arsenic through consumption of fish from a creek receiving water from the former mine and for consumption of water from the well fields for the city of Juneau. Despite the use of conservative assumptions required by EPA, all estimates for consumption of water affected by arsenic in the former mine outfall were within the cancer risk range often used as a guideline by regulatory agencies such as EPA (i.e., one in a million [10–6] to one in ten thousand [10–4] risk of cancer over background cancer rates) and risk estimates for consumption of fish were much lower than the target risk level of 10–6. Furthermore, risk estimates for consumption of arsenic in drinking water affected by the outfall were demonstrated to be lower than background risks associated with exposure to arsenic in Alaska’s drinking water.

Conducted a baseline assessment to evaluate human health risks associated with the planned operation of a gold mine in southeast Alaska that would include discharge of treatment water containing arsenic to the marine environment near an important commercial fishing area. Potential human health risks associated with arsenic bioaccumulation into fish collected from the dilution zone of the outfall were evaluated. Critical aspects of the assessment included recognition of the fact that the area potentially affected by the outfall would be a tiny fraction of the total fishing area (i.e., <0.002 percent). Use of this fractional intake estimate together with estimates of the proportion of arsenic in seafood that might occur in toxic inorganic forms and a range of representative fish consumption rates resulted in excess cancer risk estimates for consumption of inorganic arsenic in seafood well below levels of concern (i.e., risk estimates were less than 10–9). The assessment also provided a discussion of how risks associated with consumption of arsenic would be further reduced when the uncertainties in the toxicity value for arsenic are taken into account.

Provided technical support for a private client in the RI/FS process at a major Superfund site in Montana that is contaminated with arsenic, cadmium, and lead. Prepared detailed technical review comments on risk assessment conducted by contractors for the regulatory agency and assisted in preparing scoping documents suggesting use of site-specific information to conduct more accurate and technically defensible approaches than default approaches suggested in agency guidance. Also evaluated uncertainties associated with EPA’s carcinogenic slope factor for arsenic. Assisted in an investigation of the dietary sources of arsenic in Taiwanese study populations that formed the basis for EPA’s toxicity values for arsenic. This study included chemical analyses of organic and inorganic arsenic in yams and rice thought to be dietary staples of the study population. Findings from this study will be used by the client in petitioning EPA for modifications in the oral carcinogenic slope factor for arsenic. Conducted an evaluation of the potential for arsenic in terrestrial plants to be detoxified by methylation to better characterize the risks associated with consumption of garden vegetables.

Prepared a detailed evaluation of recent data to assess the risks associated with arsenic in soil for a site in Oklahoma contaminated with arsenic, cadmium, lead, and zinc. Evaluated new epidemiologic data and dietary information suggesting that use of the current carcinogenic slope factor may result in overestimates of more than an order of magnitude. Also considered the implications of data on reduced bioavailability of arsenic in soil as compared with water, metabolic data suggesting a threshold for arsenic toxicity, and new data on soil ingestion rates.

Collaborated on hazard assessment and exposure assessment for a lead-contaminated waste site in California. Prepared a case study of remediation options taken for similar sites in the state.

Acted as task manager in a review of the scientific basis for the EPA Office of Drinking Water standard for lead conducted for the American Association of Water Works. Wrote sections of the report critiquing the evidence used by EPA in supporting the target blood lead level of 10-15 mg/dL.

PCDD/F and Pentachlorophenol (PCP)

For a private client in Michigan, currently working on a mulitpathway risk assessment where the primary issue is exposure to PCDD/Fs in soil and in a river food chain environment. Working with a group of toxicologists and with the Michigan Department of Environmental Quality to identify the most accurate and appropriate means to calculate risk estimates. As part of the process, considering findings of a comprehensive biomonitoring study conducted by the University of Michigan entitled the UM dioxin exposure study (UMDES), which is a resource in determining site specific area use values as well as actual body burdens in individuals from the area.

Managed an upland investigation for a former pulp and paper mill in Ketchikan, Alaska, where Exponent scoped and completed a focused sampling effort for a fast-track site characterization and risk assessment. Supported negotiations with agency project managers to apply a decision-framework approach to the investigation, including use of source material sampling to focus on limited chemicals and areas of concern; accurate characterization of offsite sources of PCDDs, PCDFs, and arsenic; appropriate comparisons with background concentrations for metals and PCDDs and PCDFs; and use of realistic exposure estimates in risk estimates. As lead human health toxicologist for an investigation of marine areas at the site, evaluated risks posed by chemicals in sediments that might bioaccumulate into fish or shellfish. Despite the use of conservative assumptions required by EPA regarding consumption of fish and shellfish, application of an appropriate use factor resulted in risk estimates within levels considered acceptable to regulatory agencies, and no further evaluation was recommended. Described project approach and responded to community concerns at several public meetings and availability sessions.

Acted as lead toxicologist for two risk assessments of hazardous waste sites in Oregon. Managed preparation of a baseline risk assessment conducted for a former wood-treatment facility that used PCP, creosote, and arsenical fungicides. Uncertainties in the slope factor for PCDDs and PCDFs and evaluation of the comparative risks associated with consumption of fish and crayfish from reference locations were key issues in selecting cleanup levels at the 10-4 level for PCDDs in soil and in indicating that cleanup of sediments was not needed based on human health. Developed a screening level human health risk assessment for a hazardous waste site located in a unique desert environment. Past releases included process sludges from pesticide (2,4-D) manufacturing. Potential contaminants of concern included PCDDs and PCDFs, 2,4-D, 2,4,5-T, TCE, and benzene. The assessment included evaluation of all potential exposure pathways, and it was concluded that no additional investigation was needed.

Conducted human health risk evaluations and pathway analyses in support of an evaluation of costs and benefits of bioremediation of PCP-contaminated soil versus excavation and disposal at former wood treating facilities on the West Coast.

Developed educational materials, including seminars on PCBs, dioxin, and PCP; chronologies of the development of scientific knowledge on PCP, aromatic amines, and the dermal and cardiovascular effects of TCDD; and exhibits used by attorneys and by scientific experts in litigation for private clients including major chemical manufacturers and associations.

Researched and prepared a 76-page review of the toxicologic and epidemiologic literature that investigated an association between exposure to TCDD and adverse effects on the cardiovascular system as part of litigation involving putative exposure to TCDD. Also reviewed and abstracted more than 30 epidemiologic studies on TCDD and chlorinated phenoxy herbicides.

PCBs and Pesticides

Completed a comprehensive human health risk assessment evaluating potential worker exposure to PCBs discovered in concrete joint compound in a flightline area for commercial aircraft in Washington. Developed and applied risk assessment approach for novel exposure pathways, including contact with surfaces as measured by wipe samples. Researched current regulatory guidance within EPA for non-liquid PCBs and evaluated applicable assessments conducted nationwide. Site characterization suggested limited migration potential for PCBs from joint compound. The risk assessment results supported phased removal of PCB-containing material that was both health-protective and practical.

Provided toxicological support in a sensitivity analysis of PCB risk assessments. These analyses identified components of the risk assessment method that have the greatest influence on PCB cleanup levels. Risk analyses were also compared with the 1 mg/kg cleanup level typically applied for PCBs in residential soils to evaluate the relative advantages of application of risk-based or ARAR-based cleanup levels.

Multiple Chemical Investigations

Collaborated on a preliminary risk assessment that evaluated the human health risks associated with exposure to TCE, arsenic, and PCBs in material used as fill in construction of a roadway in Anchorage, Alaska. Risks to residents and workers were found to be well below levels of concern (i.e., risk estimates were below 10–6), and no further investigations were recommended.

Managed a program providing technical enforcement support to EPA Region 10 on a wide range of sites regulated under CERCLA or RCRA. Responsible for staffing, supervision of budget preparation, quality control on technical deliverables, and oversight of invoices and progress reports. As a toxicologist and risk assessor on this project, managed multidisciplinary technical reviews of RI/FS project documents, including risk assessments, site inspections, sampling and analysis plans, quality assurance project plans, and work plans. Represented EPA in negotiations regarding the approach to be used in human health risk assessments for several sites and have advised contractors for PRPs on development of work plans for risk assessments, including the identification of contaminants of concern, identification of ARARs, selection of appropriate toxicity values and exposure pathways, evaluation of detection limits to determine whether the limits were low enough to evaluate risks or hazards posed by exposure to contaminants onsite, and the development of site-specific cleanup levels.

Regulatory Evaluation and Detailed Exposure Assessment

Collaborated on a review to determine how gastrointestinal absorption of contaminants is reduced when the contaminants are adsorbed to soil. Contaminants evaluated included lead, arsenic, chromium, PCP, and benzo[a]pyrene. Significant reductions were identified for lead and arsenic, and implications for risk assessments of these contaminants were discussed.

Collaborated on devising a system to rank contaminated sediments in Puget Sound, Washington, based on the toxicologic properties of contaminants and the potential for exposure. Wrote sections of the report presenting the method for ranking sediments on the basis of their potential to cause adverse effects in humans consuming seafood from contaminated areas. The ranking system will be used by the State of Washington to develop priorities for sediment remediation.

Reviewed and evaluated studies on the carcinogenicity and mutagenicity of toxic agents to be categorized for regulation by OSHA. Audited toxicology and mutagenicity studies submitted to EPA in support of pesticide registration.

Conducted a review to determine the meaning of significant risk of cancer to workers under OSHA’s revised generic cancer policy and as interpreted by health directorates in other countries.

Coordinated with authors in the publication of a document on research needs in the area of transport and fate of organic pollutants in the environment. Edited and revised the article for accuracy. The document was used to develop a federal EPA budget for research projects on transport and fate.

Represented the National Women’s Health Network before the FDA at a public hearing on toxic shock. Maintained national speaker’s bureau and spoke at the College of William and Mary and the University of Toronto on occupational health issues. Advised National Women’s Health Network members and public on toxicological questions, most of which focused on reproductive health and maternal and child health.

• Society of Toxicology
• Member Advisory Counsel to the Minnesota Department of Health Environmental Tracking and Biomonitoring