When administered orally to male rats at 1.6 to 4.8 mg/kg, the [1R,trans], [IRS,trans], [lR.cis], and [IRS,cis] isomers of the potent pyrethroid insecticide permethrin [3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] are rapidly metabolized, and the acid and alcohol fragments are almost completely eliminated from the body within a few days. cis-Permethrin is more stable than trans-permethrin and the cis compound yields four fecal ester metabolites which result from hydroxylation

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UEDA, GAUCHAN, CASIDA acids, terpene carboxylic acids and their glucuronides, and terpene alcohols as their glucuronides or sulfates. About 2% of the 14C appears as expired products, probably 14CC>2, and this portion arises from methyl, chloromethyl, or dichloromethyl substituents in the original toxaphene components. On the assumption that most of the toxaphene components are polychlorobomanes related to the identified 2,2,5-endo,6-exo,8,9,10-heptachlorobornane and in light of the extensive or even complete metabolic dechlorination of some components, a portion of the terminal metabolites may be monocyclic or acyclic compounds.Even though most of the toxaphene components undergo rapid metabolism in mammals, there are probably large rate differences for metabolism of the various components. The components of highest toxicity are presumed to be those that combine appropriate configurations for disruption of nerve activity with some degree of resistance to metabolism. However, limited evidence from studies with toxicants A and B indicates that they are no more persistent in rats than most of the other toxaphene components. A portion of the dose of these compounds is excreted in feces without metabolism. Some of the metabolites have gc properties similar to those of other toxaphene components. Thus, it is likely that tissue residues will include metabolites formed by dechlorination that fall with-LITERATURE CITED

Radiocarbon from 14C-carbonyl-and 14C-methylene-labeled preparations of (1 RS)-trans-and (1PS)ci's-permethrin, administered to laying hens for 3 consecutive days at 10 mg/kg for each dose, is largely eliminated from the body within 1 day after the last dose, a portion as 14C02. The excreta contain all and the eggs most of the following compounds identified by thin-layer cochromatography with authentic standards and specific enzymatic hydrolysis: the unmetabolized pyrethroids; cis-permethrin hydroxylated at the 4'-position, at the methyl group trans to the carboxyl, and at both of these sites; the dichlorovinyl acids and their derivatives hydroxylated at the trans or cis methyl group; phenoxybenzyl alcohol,