The lungs as a target for the toxicity of some organophosphorus compounds

Abstract

During the toxicological investigations which followed the malathion poisoning episode in Pakistan (Baker et al., 1978), it was discovered that in addition to their ability to potentiate the cholinergic toxicity of malathion (Aldridge et al., 1979), some trimethyl and triethyl phospho-rothioates produced a form of toxicity which was unusual for organophosphorus compounds, in that they caused lung damage leading to deaths in respiratory distress 3 to 5 days after the administration of a single, relatively small dose (rat oral LD50’s generally around or below 100 mg/kg) (Verschoyle & Cabrai, 1982). Trimethyl and triethyl phosphorothioates are potential impurities in dimethyl and diethyl thiono-phosphorus insecticides. They have been detected, along with other contaminants, in technical or formulated samples of several commercial insecticides, such as malathion, phenthoate, acephate, fenitrothion, and diazinon (cf. Aldridge & Nemery, 1984). The specific pulmonary toxicity of trialkyl phosphorothioates has been confirmed by other investigators, and its characteristic features have been reviewed (Aldridge & Nemery, 1984; Aldridge et al., 1985a).

Most studies described herein were conducted at the Medical Research Council Toxicology Unit in Carshalton, Surrey, U.K. under the supervision of Dr. W.N. Aldridge.