Bioassay of the Blood from Cattle Treated with Am. Cyanamid 12, 880

Abstract

This systemic compound, known chemically as O,O-dimethyl S-(N-methylcarbamoylmethyl)phosphorodithioate (also called dimethoate) was administered to cattle by oral, intramuscular, and intravenous routes. Blood was taken from animals at stated intervals following treatment and bioassayed with the stable fly (Stomoxys calcitrans (L.)) as the test organism. The blood levels determined by radiometric measurement of p³²-labeled 12,800 were lower than those determined by bioassay. An unknown metabolite(s) in the blood was found to be approximately 40 times as toxic as the parent compound to stable flies. Am. Cyanamid 12,880 and the metabolites toxic to stable flies were not detectable by the procedure after 24 hours. The toxic materials were detectable for a longer period when the parent compound was administered orally than when it was given by intramuscular or intravenous routes.