Genotoxic effects of malathion: an organophosphorus insecticide, using three mammalian bioassays in vivo.

The genotoxic effects of malathion was evaluated using chromosome aberration, sister chromatid exchange (SCE) and sperm abnormality assays in mice. All the three acute doses (2.5, 5 and 10mg/kg) of malathion tested in the present study, induced significant dose-dependent increase in the frequency of chromosome aberrations and sperm abnormalities, but did not affect the total sperm count. The highest acute dose induced a >12-fold increase in the frequency of chromosome aberrations, two-fold increase in the frequency of SCEs and four-fold increase in the frequency of sperms with abnormal head morphology following intraperitoneal (i.p.) exposure. Further, a significant increase in the frequency of SCEs was observed, but the increase was not dose-dependent. At higher doses, malathion induced a moderate delay in cell cycle as evident from the increase in average generation time (AGT). The present findings suggest that technical grade malathion is a potent genotoxic agent and may be regarded as a potential germ cell mutagen also.