Abstract: OBJECTIVE: To invesgate the genotoxicity of dichlorvos(DDVP), dimethoate(DM) and malathion(Mal) in HepG2 cells alone and in combination, and to elucidate the combined genotoxic effects. METHODS: Comet assay(single cell gel electrophoresis assay) was adopted to evaluate the genotoxicity of dichlorvos(DDVP), dimethoate(DM) and malathion(Mal), the images were collected and then analyzed by CASP software. The 2×2 factorial analysis experiment was used to investigate their combined genotoxic effects. RESULTS: DDVP, DM and Mal all induced obvious DNA damage in HepG2 cells after treatmemt for 4 h. At the two higher concentrations of each pesticide, these parameters(percent of Tail DNA, Tail Length and Olive Tail Moment) measuring DNA damage were significantly more serious compared with solvent control. Factorial ANOVA revealed that at lower mixed dose, no interaction was noted between DDVP and DM. But DDVP and Mal, also DM and Mal both exerted synergistic effect; while at higher mixed dose, antagonistic effect were found between DDVP and DM, DDVP and Mal, as well as DM and Mal. CONCLUSION: DDVP, DM and Mal could induce DNA damage both alone and in combination, but the combined effects varied with the mixture concentration.

Key words: dichlorvos, dimethoate, malathion, genotoxicity, comet assay