Toxicologic evaluation of a microencapsulated formulation of methyl parathion applied dermally to cattle.
Acute toxicity studies in newborn calves and 2- to 3-year-old cattle were conducted with methyl parathion (O,O-dimethyl O-(p-nitrophenyl) phosphorothioate) in the form of a 22% microencapsulated slurry used in a manually operated sprayer. Twelve calves and 9 cattle were tested. The minimal toxic dosages were 4 L of a 0.5% concentration for calves and 10 L of a 0.25% concentration for mature cattle. At all toxic dosages, cholinesterase activities were decreased--that of the calves to 0 and that of the cattle to 50% of base line or less. Weight losses 2 weeks after single exposures to the treated cattle ranged from 6.5% to 11.5% of total body weight. Absorption of the formulation in its entirety or its metabolic products resulted in a possible interference with feed utilization.
D000287:Administration, Topical; D000818:Animals; D002214:Capsules; D002417:Cattle; D002418:Cattle Diseases / Q000139:chemically induced*; D003967:Diarrhea / Q000139:chemically induced / Q000662:veterinary; D005260:Female; D008297:Male; D010278:Parathion / Q000008:administration & dosage / Q000633:toxicity*
D002214:Capsules; D010278:Parathion