Dermal Absorption from Pesticide Residues

Abstract

In its regulatory role the United States Environmental Protection Agency is the repository for a large collection of dermal absorption data supplied by pesticide registrants. Many of these studies followed a common procedure measuring dermal absorption in vivo into laboratory rats as a function of both the amount of pesticide applied and the exposure time. In this chapter, example registrant data are presented and analyzed. For the 18 pesticides examined in this study, the relationship between systemic absorption and applied dose was different for pesticides that are liquids and those that are solids at skin temperature. For both groups, the amount of pesticide in skin increased proportionally with applied dose. Systemic absorption of liquid pesticides also increased with applied dose. However, for solid pesticides systemic absorption was a weaker function of applied dose and in some cases was independent of applied dose. Finally, a simple method for estimating the maximum systemic absorption using a pesticide’s permeability coefficient and water solubility under-estimated the amount of dermal absorption for most doses of many of the pesticides investigated in this study.