Distribution and metabolism of trans- and cis-permethrin in lactating Jersey cows.

Radiocarbon from I4C-acidand 14C-alcohol-labeled preparations of transand cis-permethrin administered orally to lactating Jersey cows for three consecutive days at 1.0 mg/kg is largely eliminated from the body within 12 or 13 days after the initial treatment. Milk and fat residues, although relatively low, are higher with cisthan with trans-permethrin and consist almost entirely of unmetabolized compound. cis-Permethrin hydroxylated at the methyl group trans to the ester functionality also appears in trace levels in milk. Major excreted metabolites (each 8-2870 of the administered radiocarbon) from both isomers are: the esters hydroxylated at the trans methyl group; the acid moieties hydroxylated a t the cis methyl group and the corresponding y-lactones; 3-phenoxybenzyl alcohol; the glutamic acid conjugate of 3-phenoxybenzoic acid. An additional 13 excreted metabolites of trans-permethrin and 10 of cis-permethrin are tentatively identified.