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Benchmark dose (BMD) analysis is used to determine levels of exposure to environmental contaminants associated with increased public health risk. In this study we used a benchmark approach to evaluate the risks associated with prenatal exposure to polychlorinated biphenyls (PCBs). We evaluated for intellectual impairment a cohort of children whose prenatal PCB exposure had been assessed from biologic specimens. We calculated BMDs and lower-bound confidence limits (BMDLs) for four end points using four sets of risk criteria. BMDLs were estimated using three different statistical methodologies. The BMDs and BMDLs were remarkably consistent across the four end points for each set of risk criteria, but differed substantially for the different risk criteria. The proportion of the sample considered at risk ranged from 9.8% for the least protective criteria to 74.1% for the most protective. Two methodologies, likelihood ratio and bootstrapping, generated generally similar BMDLs. BMD analysis provides a straightforward, reliable method for evaluating levels of exposure associated with increased public health risk. In the analyses performed in this study, the number of individuals considered at risk depended more on the risk criterion selected than on the outcome assessed. Key words: benchmark dose analysis, dose—response, environmental contaminants, in utero exposure, organochlorine contaminants, polychlorinated biphenyls, risk analysis. Environ Health Perspect 110:393–398 (2002). [Online 8 March 2002] [ABSTRACT FROM AUTHOR]

Abstract: Serum samples from 285 4-year-old Michigan children were evaluated for levels of 11 environmental contaminants. Polychlorinated biohenyls (PCBs) were found in half the samples tested; polybrominated biphenyls (PBBs) in 13-21 percent; dicholorodiphenyl trichloroethane (DDT), in more than 70 percent. Nursing (Mothers' milk) was the principal source of these exposures. Congener specific analysis documented the presence of at least one highly toxic PCB congener, 2,3',4,4',5-pentachlorobiphenyl. The data demonstrate the multigenerational impact of female exposure to persistent organic environmental contaminants. [ABSTRACT FROM AUTHOR]