Dietary Exposures to Selected Metals and Pesticides. D. L. MacIntosh, Emory University School of Public Health, Atlanta, GA; J. D. Spengler and H. Özkaynak, Harvard School of Public Health, Boston, MA; and P. B. Ryan, Emory University School of Public Health, Atlanta, GA
Food consumption data measured by food frequency questionnaires completed by approximately 120,000 participants in two ongoing epidemiological studies and contaminant residue data collected as part of the FDA Total Diet Study were combined to estimate the distribution of average daily dietary exposures to arsenic, cadmium, lead, mercury, chlorpyrifos, diazinon, malathion, dieldrin, DDE-p,p', lindane, and heptachlor epoxide for a large population of U.S. adult males and females. The results suggest that dietary intakes of these contaminants are highly variable among people; approximately lognormally distributed with geometric standard deviations of about 2.5. Thirteen percent of the estimated exposures for As and 1% of the Hg intakes exceeded the respective EPA reference dose for non-cancer health effects, while 20 and 50 percent, respectively, of the estimated As and dieldrin exposures exceeded levels that may produce cancer risks greater than 10-4. The accuracy of the estimated chronic dietary exposures to inorganic arsenic and organic mercury were validated by comparing the predicted intakes to biomarkers of chronic exposure, toenail arsenic and mercury, for 1,350 members of the study population. Spearman correlation coefficients between estimated intakes and concentrations of arsenic and mercury in toenails were 0.24 and 0.52, respectively. These results indicate that a short, self-administered food frequency questionnaire may be useful for characterizing potential health risks posed to individuals by contaminants for which total exposure is dominated by the food ingestion pathway and may eventually lead to a unique opportunity to study associations between toxicants in food and risk of chronic disease.