Preliminary Studies of the Toxicity of Carbophenothion and Methyl Trithion in Livestock2

Abstract

Carbophenothion suspension sprays were toxic to dairy calves at 0.05% and higher concentrations whereas Methyl Trithion® (S-(p-chlorophenylthio)methyl O,O-dimethyl phosphorodithioate) emulsion sprays produced no signs of toxicosis in dairy calves at 0.25% and 0.5% concentrations but with moderate cholinesterase depression. Dairy calves were poisoned with a Methyl Trithion drench at 25 mg./kg. with marked cholinesterase depression. Cattle were safely sprayed with 0.05% and 0.1% suspension sprays of carbophenothion and 0.5% emulsion sprays of Methyl Trithion with slight to no cholinesterase depression, but 1.0% suspension sprays of carbophenothion were toxic to cattle. Goats were safely dipped in a 0.1% emulsion of Methyl Trithion with moderate cholinesterase depression. Sheep were poisoned with carbophenothion as a drench at 25 mg./kg. but tolerated carbophenothion given as 1 drench at 10 mg./kg., with marked depression of cholinesterase activity. Sheep tolerated Methyl Trithion given as a drench at 25 mg./kg. with moderate depression of cholinesterase activity.