Regional Variation in Percutaneous Penetration in Man

Abstract

Pesticides labeled with radioactive carbon (¹⁴C) (parathion, malathion, and carbaryl) were applied on the skin of volunteers. The experimental variable studied was the effect of anatomic site; all other factors (dose, solvent, and analytic method) remained constant. Quantitation was based on urinary recovery of the ¹⁴C. The forearm was used as the frame reference. The palm, of which the thick stratum corneum is allegedly almost impenetrable, allowed approximately the same penetration as the forearm. The abdomen and dorsum of the hand had twice the penetration of the forearm, whereas folliclerich sites, including the scalp, angle of the jaw, postauricular area, and forehead, had fourfold greater penetration. The intertriginous axilla had a fourfold to sevenfold increase; the scrotum allowed almost total absorption.