Sensitization risk of pyrethroid insecticides.

Abstract

Although the true incidence of'contact dermatitis from pesticides (I, 2) is unknown, the main causes arc now fungicides, particularly thiophthalimides (captan, difolatan and foIpet), bis-dithiocarbamates (maueb, zineb and mancozeb) and benomyl (3, 4). instead of organophosphates and chlorinated hydro­ carbons (5-7). Sensitization to those derived from plants (pyrethrum, nicotine, rotenone and quassia) is rare and to pyrethroids unknown. Pyrethroids arc neurotoxic synthetic compounds with broad-spectrum insecticidal activity and less toxicity to mammals than organophosphates (8). They are rapidly metabolized and only partially ab­ sorbed from the GI tract (9). They have largely been used since 1973 to control agricultural pests and to protect stored products. Over l,OOO pyrethroids have been synthesized and some (e.g., cypermethrin, delta­ methrin, fenpropathrin and feDvalerate) have an C(­ cyano group attached to the 3-phenoxybenzyl alco­ hol of the molecule (10). These possess greater photo­ stability, less volatility and higher insecticidal activity than those pyrethroids lacking an C(-cyano group (e.g., allethrin, bioresmethrin, cismethrin, fenothrin, permethrin and resmethrin). The aim of the present study was to establish the irritation and sensitization risks of the most widely used pyrethroids. Patients and Methods