Enhancing or Blocking Effect of Fenvalerate on the Subsequent Percutaneous Absorption of Pesticides in Vitro

Abstract The percutaneous absorption of pesticides has been receiving much research attention. However, most work is conducted with single exposures and potential interactions of previous pesticide exposure have received little attention. In the present study, the effect of in vivo pretreatment of the skin with a 3% fenvalerate in ethanol or a 3% parathion in ethanol solution on carbaryl, fenvalerate, lindane, and parathion absorption was studied in vitro using weanling pig skin in a flowthrough diffusion cell system. Concentrations of 40 or 400 μg/cm 2 of carbaryl, fenvalerate, lindane, and parathion in ethanol were applied topically. Environmental conditions of air and perfusate temperature (37°C), relative humidity (60%), flow rate (4 ml/hr), and Kreb′s-Ringer bicarbonate buffer with 4.5% bovine serum albumin medium were controlled. The total absorption of these pesticides, both ethanol control and fenvalerate or parathion pretreated, increased proportionally with the dose; however, the absorption efficiency (fraction of applied dose absorbed) decreased as the dose increased. At both doses, fenvalerate pretreatment had little or no effect on carbaryl and fenvalerate absorption; however, parathion absorption was significantly decreased in fenvalerate-pretreated skin ( P P ≥ 0.05) of parathion absorption between the parathion pretreatment and the fenvalerate pretreatment. Lindane absorption increased at the 40-μg dose and significantly increased at the 400-μg dose ( P 2 Furthermore, comparing ethanol control data with previous results indicates that prolonged skin treatment with ethanol significantly increases parathion absorption ( P