Detection of kidney damage by malathion impurities using a microdissection technique.

O,O,S-Trimethylphosphorothioate (OOS-Me) and O,S,S-trimethylphosphorodithioate (OSS-Me) are impurities in technical grade malathion and related insecticides which have been shown to cause delayed death in rats following a single oral dose of 40-60 mg/kg. In connection with studies on the mode of action of these compounds, work on the microdissection and examination of nephrons was carried out. Nephrons from impurities-treated rats showed swelling, distortion and distension of glomeruli, as well as narrowing of the first part of the proximal tubule (swan neck). These results were similar to those observed from kidney tissue obtained from cadmium-chloride-treated rats and are indicative of OOS-Me and OSS-Me-induced kidney tubule damage.