Cytogenetic effects induced by the natural pyrethrins and the synthetic lambda cyhalothrin in mice in vivo

Abstract

The potential genotoxicity of the natural pyrethrins and the synthetic lambda (λ) cyhalothrin was evaluated in mice in vivo. Single oral treatment with the doses 45, 90, 180 mg kg-1 b.wt. of pyrethrins and 1.25, 2.5, 5 mg kg-1 b.wt. of λ cyhalothrin (1/8, 1/4, 1/2 LD50) induced modest but statistically significant increase in the frequency of sister chromatid exchanges (SCE's) in bone-marrow cells. Such frequency reached 8.20±0.41 and 8.67±0.24 per cell after treatment with the highest tested dose of both insecticides respectively compared with 5.32±0.28 for the control. Marked induction of SCE frequency (12.40±0.90) per cell was observed after treatment with mitomycin C which is used as a positive control. Single oral treatment with the doses 90, 180 mg kg-1 b.wt. of pyrethrins and 1.25, 2.5, 5 mg kg-1 b.wt. of λ cyhalothrin, induced significant increase in the percentage of chromosomal aberrations in mouse bone-marrow. With respect to germ cells only the highest tested dose of both insecticides (1/2 LD50) induced a significant percentage of chromosomal aberrations in mouse spermatocytes after single oral treatment. Chromosomal aberrations were also recorded after repeated treatment. For studying sperm abnormalities mice were orally treated for 5 consecutive days with 22.5, 45, 90 mg kg-1 b.wt. of pyrethrins and 0.63, 1.25 and 2.5 mg kg-1 b.wt. of λ cyhalothrin. Significant percentage of sperm abnormalities was observed after treatment with the 2 higher doses of both insecticides. In conclusion, both insecticides pyrethrins and λ cyhalothrin induced some clastogenic effects with the high tested doses.