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Role of metabolic activation, covalent binding, and glutathione depletion in pulmonary toxicity produced by an impurity of malathion.

Authors
Type
Published Article
Journal
Toxicology and applied pharmacology
Publication Date
Volume
72
Issue
3
Pages
476–483
Identifiers
PMID: 6710498
Source
Medline
License
Unknown

Abstract

O,O,S-Trimethyl phosphorothioate (OOS-TMP) is an impurity present in widely used organophosphorus insecticides such as malathion. Oral treatment of rats with the compound produces prominent bronchiolar epithelial necrosis. Following the administration of [3H]OOS-TMP to rats, substantial amounts of radiolabeled material were covalently bound to lung with a concomitant depletion of glutathione (GSH). Other organs showing significant covalently bound radioactivity were liver, kidneys, and ileum. The maximal accumulation occurred in the tissues within 6 hr, and reached a plateau between 6 and 12 hr. Pretreatment of rats with either phenobarbital or piperonyl butoxide decreased the level of radiolabeled material bound in lung, GSH depletion, and the toxicity of OOS-TMP. These results suggest that the covalent binding is due to a metabolite(s) of OOS-TMP and that the metabolite(s) is involved in the mechanism of toxicity of OOS-TMP. Pulmonary GSH may play a protective role against OOS-TMP induced lung toxicity.

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