Uncertainties in health-risk assessment: an integrated case study based on tetrachloroethylene in California groundwater.
Population risk to an environmental contaminant is represented as the product of a source term; the exposure function, which converts the source into a lifetime-equivalent contact rate in the population; the fraction metabolized; the toxic potency associated with the delivered dose; and the size of the exposed population. Using case studies for contamination of groundwater in California with tetrachloroethylene (PCE), the combined uncertainty in exposure and dose-response models is characterized. Three key issues are addressed: (a) uncertainty in quantifying pathway exposure factors that relate measured environmental concentrations to levels of contact in the exposed population; (b) the uncertainty in the human dose-response models derived from animal data; and (c) an overview of important contributors to the overall uncertainty in population risk estimates.
McKone
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Lawrence Livermore National Laboratory, University of California, Livermore 94550.
Bogen
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D000280:Administration, Inhalation; D016902:Air Pollution, Indoor / Q000032:analysis; D000818:Animals; D002140:California; D002273:Carcinogens / Q000633:toxicity; D006801:Humans; D008954:Models, Biological; D009010:Monte Carlo Method; D009369:Neoplasms / Q000139:chemically induced / Q000453:epidemiology; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000453:epidemiology; D012306:Risk; D013750:Tetrachloroethylene / Q000032:analysis / Q000493:pharmacokinetics / Q000633:toxicity*; D014481:United States; D014484:United States Environmental Protection Agency; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*; D014881:Water Supply / Q000032:analysis*
D002273:Carcinogens; D014874:Water Pollutants, Chemical; D013750:Tetrachloroethylene