Studies on pesticide residues. 1. Excretion of pesticides in milk following dermal treatment of dairy cattle with coumaphos and dioxathion

Abstract

Dairy cattle were sprayed with 0·025% coumaphos, 0·050% coumaphos or 0·075% dioxathion, concentrations recommended for the control of ectoparasites of cattle, and excretion in milk was examined in samples taken during a 5-day post-treatment period. Maximum concentration and total excretion of coumaphos in milk occurred at the first sampling, 5 hr after treatment, whereas maximum total excretion of dioxathion was observed at the third sampling 29 hr after treatment. Levels of both pesticides in milk declined rapidly and were not detectable (<O ·005 p.p.m.) 70 hr after exposure. No differences were observed between the excretion patterns of coumaphos applied as wettable powder and emulsion formulations. The concentration of pesticide in milk was shown to be a function of concentration applied, quantity of milk produced and time of sampling after exposure.