In vivo and in vitro cytogenetic effect of supermethrin.

The synthetic pyrethroid insecticide supermethrin (RS)-alpha-cyano-3-phenoxybenzyl-(1RS)-cis-3 (2, 2-dichlorvinyl)-2, 2-dimethyl cyklopropane carboxylate, was tested for its clastogenic ability by in vivo and in vitro assays. In vivo assay consisted of chromosome analysis in sheep bone marrow cells after six weeks subchronic oral administration of 200 mg/kg or 300 mg/kg. The results were compared to induction of chromosome aberrations (CA) in mouse bone marrow cells after acute ip administration of supermethrin in the range 1/2 to 1/10 LD50. Small statistically insignificant increases of CA were found up to 1/2 LD50 dose for mice. Cultured sheep peripheral lymphocytes were used for in vitro clastogenicity evaluation. The final concentrations were 6 x 10(-6) mol.L-1, 6 x 10(-5) mol.L-1 and 6 x 10(-4) mol.L-1. No significant differences were detectable in supermethrin's clastogenic potency at concentrations of 6 x 10(-6) mol.L-1 and 6 x 10(-5) mol.L-1 respectively. The highest concentration was positive (P < 0.05), and a decrease of mitotic index (MI) was also observed. Supermethrin was investigated for the induction of sister chromatid exchanges (SCE) in sheep peripheral lymphocytes, but inadequate results of genotoxic potency were found. The tested pyrethroid was characterized as rather toxic than clastogenic or genotoxic.