The Metabolism of Dimethoate in Cattle

Abstract

The metabolism of P³²-dimethoate was studied following oral and intramuscular administration (10 mg./kg.) to cattle. By both routes high radioactivity was detected in the blood shortly after administration. The radioactivity, representing both total and organosoluble compounds, was observed earlier and dissipated faster in the intramuscular treatment. Chromatographic analyses of blood extracts indicated the presence of both dimethoate and unknown(s), with the latter several times more toxic than the parent compound as determined by enzymic analyses and bioassay. About 87 to 90% of the oral dose was eliminated in the urine at the end of 24 hours. The same percentage of intramuscular dose was excreted after 9 hours. The major metabolic products were dimethyl phosphate, dimethyl phosphorothioate, and several unknowns. Only 3.7 to 5% of the oral dose and about 1.1% of the intramuscular dose were eliminated in the feces. Analyses of tissues from an orally treated calf showed only very low levels (0.02 to 0.07 μg./gram) of organoextractable radioactive compounds present in the brain, liver, testes, and lungs.