Chlorpyrifos and 3,5,6,-trichloro-2-pyridinol: residues in the body tissues of cattle wearing chlorpyrifos-impregnated plastic ear tags.

Abstract

Residues of the insecticide chlorpyrifos and its metabolite 3,5,6-trichloto-2-pyridinol (pyridinol) were determined in the body tissues of Hereford yearlings at intervals after they had a 10% chlorpyrifos-impregnated plastic band attached to each ear. Each band contained ca. 3.3 g of chlorpyrifos; therefore, each animal was initially exposed to ca. 6.6 g of chlorpyrifos. Residues of chlorpyrifos were found in fatty tissues only (maximum 0.091 ppm at 2 wk biopsy) with the exception of the muscle of one animal at 5-wk posttreatment slaughter that contained a residue of 0.010 ppm. Residues of pyridinol were found only in fat, liver, and kidney tissues (max 0.037 ppm in kidney at 5-wk posttreatment slaughter) and 2 heart samples each containing pyridinol residues of 0.01 ppm. Attachment of the bands to the ears resulted in moderate to severe necrosis in one or both ears of each animal.