Dietary pesticide risk assessment.

In this review, the process of dietary pesticide risk assessment has been presented and three major components of the process--estimation of pesticide residue levels, estimation of food consumption patterns, and characterization of risk based on a comparison of exposure estimates with toxicological criteria--have been identified. Each component of the process is subject to considerable uncertainty that may compromise the accuracy of the final risk assessment. In estimating pesticide residue levels, common practices range from highly theoretical models assuming that all residues are present at a predetermined level (typically at the tolerance level) to the use of market basket survey data obtained at the time the food is ready for consumption. Intermediate techniques include using actual monitoring data (usually obtained from government residue enforcement programs) and/or making corrections to estimates on the basis of actual pesticide use. Additional corrections may be used to incorporate data on the effects of post-harvest practices such as processing, washing, cooking, peeling, and transportation that have often been shown to dramatically reduce residue levels, although occasional increases in residue levels and/or formation of toxicologically significant breakdown products may also result from post-harvest practices. Food consumption estimates are typically derived from national surveys of consumer food consumption behavior and are also subject to considerable uncertainty. Food consumption estimates are often disaggregated into distinct population subgroups based on age, gender, geographic region, and ethnicity, although the accuracy of estimates for particular subgroups is commonly questioned on the basis of the adequacy of sample size. At the present time, data from the 1977-78 Nationwide Food Consumption Survey are still being used, and the incorporation of more recent data from the 1987-88 Nationwide Food Consumption Survey is being delayed due to major flaws in the study. On occasion, other food consumption surveys may be used, although they are typically much smaller in scope than the 1977-78 and 1987-88 studies and are considered less reliable. The multiplication of residue level estimates by food consumption estimates yields an estimate of human pesticide exposure. Commonly, the theoretical maximum residue contribution (TMRC) is calculated that represents the maximum "legal" exposure to pesticides. Calculation of the TMRC involves the assumptions that all pesticides legally allowed on a particular commodity will always be applied, that all residues are present at the tolerance levels, and that there are no post-harvest effects on residue levels. Often the TMRC is used as a sorting tool by the EPA in its preliminary assessment of dietary risks to pesticides.(ABSTRACT TRUNCATED AT 400 WORDS)