Famphur Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review

Famphur (phosphorothioic acid, O,(4((dimethylamino)sulfonyl),phenoyl)O,Odimethyl ester), also known as Warbex, is a systemic organophosphorus insecticide used almost exclusively as a veterinary chemical to control parasite in livestock. Only famphur and its oxygen analog, famoxon, were of toxicological significance; other famphur metabolites were 31 to 237 times less toxic, as Judged by acute oraltoxicity tests in the mouse (Mus sp.). Famphur is administered to livestock by intramuscular or subcutaneous injection, through the diet, as a dermal pour-on, or as an oral bolus. Current recommendations include the discontinuance of topical applications of famphur to cattle because of its association with primary and secondary poisoning of birds, and more research on famphur in the three areas of latent effects on treated livestock, fate and effects in aquatic ecosystems, and carcinogenicity evaluation.