Residues of Diazinon, Coumaphos, Ciodrin, Methoxychlor, and Rotenone in Cow’s Milk from Treatments Similar to Those Used for Ectoparasite and Fly Control on Dairy Cattle, with Notes on Safety of Diazinon and Ciodrin to Calves

Studies were of 3 types: insecticide application to 2 or 3 cows and milk samples carefully taken from individual cows, insecticide application to whole dairy herds and milk samples taken from cans or bulk tanks following milking by normal farm practice, and spraying of insecticide onto calves to note toxicity. Individual cow experiments showed no detectable residue in milk caused by suspensions in water of 0.25% or less methoxychlor at 2 quarts or less per cow, or by dry application of methoxychlor wettable powder. Residues of 0.15 ppm or less were caused by 0.5 or 0.2% methoxychlor suspension in a large-volume spray. Dusting whole herds with 50% methoxychlor wettable powder caused extremely small but definite residues which were probably the result of external contamination. Individual cow experiments showed very small short-lived residues in milk subsequent to spraying cows with a large volume of 0.06% diazinon suspension. Maximum apparent diazinon in milk was 0.33 ppm 1 day after a second spray treatment. In a similar experiment, 0.1 and 0.25% coumaphos sprays caused a maximum of 0.03 ppm residue in milk, with no residue found after the first 2 milkings subsequent to spraying. In a similar experiment, 0.03% Ciodrin® (alpha-methylbenzyl 3-hydroxycrotonate dimethyl phosphate) spray caused a maximum of 0.007 ppm residue in milk, which decreased rapidly within 2 days. No detectable residues in milk were caused by spraying or misting whole dairy herds with rotenone suspensions or emulsions. Complete soaking of young calves with 0.15 to 0.6% Ciodrin caused no symptoms of toxicity. Spraying calves twice with 1% diazinon emulsion (210 ml followed by 405 ml 2 days later) caused no symptoms of toxicity.