Cytogenetic effects of the insecticide methamidophos in mouse bone marrow and cultured mouse spleen cells

Abstract

The cytogenetic effect of the insecticide m etham idophos (0, S-dim ethylphosphoroam idothiolate) was studied in m ouse bone marrow and m ouse spleen cells in culture. In vivo the ability of metham idophos to induce micronuclei and sisterchromatid exchange in m ouse bone marrow was investigated. In vitro m ouse spleen cells in culture were used to assess the ability of the insecticid to induce chromosomal aberrations and sister chromatid exchange. Three different routes of application for the pure insecticide were tested so as to cover the different possibilities for human exposure to the insecticide. Intraperitoneal, oral and dermal treatment with m etham idophos caused toxicity to marrow as indicated bv a significant increase in the percentage of polychromatic erythrocytes (PEs) over that of the control. Methamidophos showed mutagenic potential as evidenced by a positive response in the micronucleus and chromosomal aberrations assays. Thus, single and multiple i.p. injections at 6 and 4.5 mg methamidophos/kg body w t., oral administration o f the insecticide for 14 consecutive days at a dietary level of 100 ppm and multiple dermal treatments (total 4) with 24 mg/kg body wt. induced a statistically significant increase in the frequency o f PEs with micronuclei in mouse bone marrow. M oreover, the tested concentrations o f m etham idophos as low as 0.25 ng/ml induced a high percentage of m etaphases with chrom osom al aberrations in cultured m ouse spleen cells. M ethamidophos is a weak inducer of SCEs in m ouse bone marrow and cultured mouse spleen cells. © 1987, Walter de Gruyter. All rights reserved.