Residue of Cypermethrin and Its Major Acid Metabolites in Milk and Tissues from Dairy Bovines Treated with Cypermethrin

A bovine feeding study was conducted to determine the magnitude of the residues of cypermethrin and its acid metabolites in milk, cream, kidney, liver, pectoral muscle, adductor muscle, peritoneal fat, and subcutaneous fat following daily oral administration of cypermethrin for 28 consecutive days. The dose levels were 5, 15, and 50 ppm (mg/kg) in the diet, which were equivalent to 1, 3, and 10 times the expected maximum intake level in animal feeds. In addition, two registered insect repellent eartags containing cypermethrin were fixed to each animal to establish the maximum conditions of exposure. The residue results were used to determine the extent of residue transfer from animal feeds into bovine milk, meat products, and meat byproducts. The residue decline rate was also measured during a recovery period following withdrawal of the test substance. Keywords: Cypermethrin; metabolites; residues; milk/tissues