DIETARY EXPOSURES TO SELECTED METALS AND PESTICIDES

Average daily dietary exposures to 11 contaminants were estimated for approximately 120,000 adults by combining data on annual diet, as meas ured by a food frequency questionnaire, with contaminant residue data for table-ready foods that were collected as part of the annual U.S. F ood and Drug Administration Total Diet Study. The contaminants include d in the analysis were four heavy metals (arsenic, cadmium, lead, merc ury), three organophosphate pesticides (chlorpyrifos, diazinon, malath ion), and four organochlorine pesticides (dieldrin, p,p'-DDE, lindane, heptachlor epoxide). Dietary exposures to these contaminants were hig hly variable among individuals, spanning two to three orders of magnit ude. Intraindividual exposures to the metals, organophosphates, and or ganochlorines were estimated to be strongly correlated; Pearson's corr elation coefficients ranged from 0.28 for lindane:dieldrin to 0.84 for lead:mercury. For some of compounds (e.g., arsenic and dieldrin), a s ubstantial fraction of the population was estimated to have dietary in takes in excess of health-based standards established by the EPA. Befo re use for risk assessment or epidemiologic purposes, however, the val idity of the exposure estimates must be evaluated by comparison with b iological indicators of chronic exposure. Because of their low detecti on rate in table-ready foods, the estimated distributions of exposures for dieldrin, p,p'-DDE, heptachlor epoxide, lindane, diazinon, and ch lorpyrifos were found to be sensitive to assumed values for nondetect samples. Reliable estimates of the population distribution of dietary exposures to most other contaminants cannot be made currently, due to their low rate of detection in table-ready foods. Monitoring programs that use more sensitive study designs and population-based assessments for other subpopulations should be a priority for future research.