Conservatism in pesticide exposure assessment

Three important factors are commonly encountered in exposure assessment that when combined could overestimate the exposure to pesticides by as much as two orders of magnitude. The three factors discussed are dermal absorption from laboratory animal studies, daily dose extrapolated from partial day monitoring, and nonbolus dose from dermal or inhalation exposure. Conservatism built into the process by each of these three factors is substantiated with available empirical data. The dose overestimation from these factors varies discriminatively by exposure scenarios and peculiarities of a given chemical. It is for this reason that a generic overestimation factor cannot be ascribed. Following the empirical illustrations, the authors conclude that the most effective approach for dealing with the problem is to generate the most appropriate data possible. This means producing human rather than laboratory animal dermal absorption data, conducting full-day exposure monitoring studies, and whenever feasible generating dermal rather than oral toxicology data (or alternatively data on both oral and dermal pharmacokinetics) in those cases where the dermal route predominates.