Chlorpyrifos and 3,5,6-trichloro-2-pyridinol: residues in body tissues of swine treated with chlorpyrifos for hog louse and itch mite control.

Abstract

Residues of chlorpyrifos and its metabolite pyridinol, 3,5,6-trichloro-2-pyridinol, were determined in abdominal fat, muscle, liver, and kidney tissues of swine at weekly intervals after they had been treated with “Dursban® 44 Insecticide Formulation” (43.2% chlorpyrifos) at the rate of one ml/(22.68 kg) (50 lb) of body wt as a pour-on application for control of the hog louse, Haematopinus suis (L.) and the itch mite, Sarcoptes scabiei (De Geer). Chlorpyrifos residues (maximum 0.406 ppm at 1 wk slaughter) were found in fat tissue for 3 wk posttreatment and in muscle tissue at 1 wk posttreatment. Residues were not detected in liver and kidney tissues. Pyridinol residues (maximum 0.317 ppm at 1 wk slaughter) were present in fat, muscle (1 animal only), liver, and kidney tissues at 1 wk posttreatment and in only fat and liver tissues at 2 wk posttreatment. Residues of chlorpyrifos and pyridinol were not detected in tissues after 3 wk posttreatment. No adverse effects to the animals resulted from this type of treatment.