Metabolism of cis- and trans-cypermethrin in rats. Balance and tissue retention study

Abstract

The fate of the cis and trans isomers of the pyrethroid insecticide cypermethrin (NRDC 149), a-cyano-3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, has been studied in rats (1-5 mg/kg) by using three forms of radiolabeling (benzyl-14C, cyclopropyl-14C, and cyano-14C). Radioactivity derived from the benzyl-14C and cyclopropyl-14C labeling was rapidly eliminated, mostly in the urine. Tissue residues were generally very low, e.g., 0.01 pg/g in brain, with the exception of fat (~1 pg/g). Residues derived from the cis isomer tended to be higher than those derived from the trans isomer. The rate of depletion of the residues derived from [benzyl-14C] -cis-cypermethrin was rapid (tv2 was less than ~1 day) from all tissues except fat, from which radioactivity was eliminated with a half-life of [11][12] days. This residue was largely due to unchanged cis-cypermethrin. [cyono-14C]Cypermethrin afforded radioelimination and distribution characteristics similar to those reported for the cyanide ion.

Distribution, Metabolism and Toxic Effects of Beta-Cypermethrin in Lizards ( Eremias argus ) Following Oral Administration

“…In rats and in mice, it was known that ester cleavage was more extensive for trans-PYRs than cis-PYRs [14,45,46]. In treated lizards tissues, the T/A value was fluctuant over time (Table 2), and all of these values were less than or equal 1.58 ± 0.15 (the initial value of T/A).…”

Effects of a cypermethrin-based pesticide on early life stages of common carp (Cyprinus carpio L.)

“…1973;Bradbury and Coats 1989a). Cypermethrin is used to control pests including moths in cotton, fruits, and vegetable crops (Crawford et al 1981). It is used in public health and animal husbandry, including in marine fish production to control ectoparasites (Treasurer and Wadsworth 2004).…”

Neurotoxic Effects of Cypermethrin in Wistar Rats: a Haematological, Biochemical and Histopathological Study

“…2,3) At present, they have broad-spectrum use in agriculture, domestic and veterinary applications due to their high bioefficacy, enhanced stability, and comparatively low mammalian toxicity. [4][5][6] Pyrethroid insecticides have been divided into types I and II based on behavioral profiles of toxicity. Type I pyrethroids may cause mainly hyperexcitation and fine tremors and type II pyrethroids such as cypermethrin, produce a more complex syndrome including clonic seizures, but the signs of toxicity disappear fairly rapidly and they recover within a week.…”

“…9) In spite of the low toxicity of pyretroids, persistence of these compounds in mammalian tissues may be dangerous. 4) Permanence of cypermethrin and its fatty acid conjugates in adipose tissue, brain and liver was reported in rats. 10,11) However, several authors reviewed pyrethroid neurotixicity, concluding that pyrethroids do not accumulate in the body and their removal from nervous system as well as their excretion are rapid, even after repeated administrations.…”