The potential genotoxic/cytotoxic effect of epoxiconazole was evaluated by means of sister chromatid exchanges (SCE) following the 24 and 48 h in vitro exposure of human peripheral blood lymphocytes to epoxiconazole at concentrations of: 5, 10, 25, 50 and 100 μg. ml–1. Dimethyl sulphoxide (DMSO), used as an epoxiconazole solvent, was used as a negative control and mitomycine (MMC) as a positive control. After the 24-hour exposure, we failed to observe a significant increase in SCE frequencies in comparison with the negative control, however, the concentrations of 10—100 μg.ml–1 caused a significant decrease in the proliferation index (PI; P < 0.001). Also, the 48-hour exposure produced no significant alterations in the SCE frequencies in comparison with the control. At epoxiconazole concentrations ranging from 10 to 50 μg.ml–1 we recorded a moderate to strong, dose-dependent inhibition of PI (P < 0.05; P < 0.01; P < 0.001), while at the highest dose (100 μg.ml–1) the reduction in PI compared to the control was less pronounced (P < 0.05). The reduction in PI at the concentration range of 10—100 μg.ml–1 depended on the number of cells in the M1, M2 and M3 phases of the cell cycle per total number of 100 evaluated metaphases. Our results indicated a significant cytotoxic or cytostatic effect on human peripheral blood lymphocytes.
