Improving the management of pesticides in foods

Improvements in pesticide residue risk assessment practices should improve the scientific basis for managing pesticide residues in foods and the FQPA provides a blueprint for making such improvements. While most of the FQPA provisions are considered in theory to represent improvements in the risk assessment process, the practical adoption of methods to comply with such 

The additional data provided from the probabilistic exposure assessment also require greater interpretation. Under provisions of FQPA, the EPA is not allowed to grant tolerances for pesticides unless the aggregate and cumulative 

The ability to use probabilistic approaches to assess dietary pesticide exposure has also changed much of the emphasis of pesticide risk assessment practices from assessing long-term (chronic) exposure to short-term (acute) exposure. Deterministic approaches worked well with chronic assessments since the day-to-day variability in food consumption patterns and the variability of pesticide residue levels tended to average out over the course of a 70-year exposure period. Deterministic approaches have also often been used in the assessment of acute dietary risk by assuming an upper percentile level of food consumption and the maximum detected or allowable level of residue. The point estimate determined in this manner is then compared with the RfD to determine the acceptability of exposure under the specified conditions. 

It is most appropriate for the exposure estimates determined from acute probabilistic assessment techniques to be compared with acute single-day RfDs to determine the acceptability of such exposures. Unfortunately, since accurate acute RfDs for most pesticides have not been determined, the exposure estimates are often compared with RfDs derived from longer-term (28 to 90 days) or chronic toxicology studies. In most cases, the acute RfDs may be much higher than those obtained from longer-term studies. This is particularly important in cases where pharmacokinetic factors such as absorption, distribution, biotransformation, and excretion of a pesticide have been established and demonstrate that repeated exposure to the pesticide could cause an increase in 

In addition to the need for scientific improvements to allow probabilistic risk assessments to be properly performed and interpreted, there also exists a need to educate stakeholders about what the US system for tolerance establishment and monitoring does and does not do. In simplest terms, the US system can be described as a food quality system but not necessarily a food safety system. This results from the fact that the pesticide tolerances are not safety standards but rather exist as enforcement tools that allow an assessment of how well pesticide application regulations are adhered to. Violative residues demonstrate the likelihood of pesticide misuse but should not be considered, in the vast majority of cases, to represent unsafe residues. Safety considerations govern whether or not the use of pesticides on specified commodities will be permitted tolerances, when granted, serve as indicators of good agricultural practices rather than as toxicological benchmarks. 

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