CYTOGENETIC EFFECTS OF DELTAMETHRIN ON RAT BONE-MARROW

Deltamethrin, a synthetic pyrethroid insecticide, was administered to adult female albino rats as a single i.p., s.c., or oral dose of 5.6, 8.4, or 11.2 mg/kg b.w. or repeated i.p. doses of 2.24 mg/kg b.w. for five consecutive days (cumulative dose 11.2 mg/kg b.w.). This treatmen t inhibited the mitotic index in a dose-dependent manner and increased the frequency of chromosome aberrations in the bone marrow at 24 h po st exposure. The parenterally (i.p. and s.c.) administered deltamethri n appeared more effective than the oral gavage for eliciting its cytot oxicity and genetic toxicity potential. The frequency of micronucleate d erythrocytes in the bone marrow was also increased at 30 h following a single i.p. dose of 5.6, 8.4, or 11.2 mg/kg b.w. The most prevalent abnormality observed in this study was endomitotic reduplication of c hromosomes which, along with mitotic inhibition and micronucleus induc tion, indicated microtubular/mitotic spindle poisoning by deltamethrin . The increased frequency of chromosome aberrations and micronucleated erythrocytes also suggests a clastogenic potential of deltamethrin. T hese observations indicate the in vivo susceptibility of mammals to th e genetic toxicity potential of deltamethrin.