A comparison of the 8-hydroxydeoxyguanosine, chromosome aberrations and micronucleus techniques for the assessment of the genotoxicity of mercury compounds in human blood lymphocytes

We compared the mechanism of action of micronuclei (MN), unstable chromosome aberrations, and 8-hydroxyde oxyguanosine (8-OHdG) levels to evaluate the genotoxicity of methyl mercuric chloride (CH3HgCl) and mercuric chloride (HgCl2) in human peripheral lymphocytes. The chromosome aberrations in human peripheral lymphocytes exposed to various concentrations of CH3HgCl or HgCl2 increased in a concentration-dependent manner and were significantly higher than the control when the cells were incubated with 1 X 10(-5) M (HgCl2) or 2 X 10(-6) M (CH3HgCl). The increase in the incidence of micronucleated lymphocytes was significant among the exposed groups, being 2 X 10(-5) M (HgCl2) and 5 X 10(-6) M (CH3HgCl) compared with the control. CH3HgCl was about 4-fold more potent than HgCl2. We determined the 8-OHdG levels in human peripheral blood mononuclear cells(PBMC) and found that they were significantly higher in the exposed groups at 1 X 10(-5) M (HgCl2) and 5 X 10(-6) M (CH3HgCl) compared with the control. A detectable (p < 0.05) increase in the level of 8-OHdG was induced by CH3HgCl at a concentration that was about 50% of the amount of HgCl2 required to produce a similar response. The data confirmed the value of the MN and/or chromosome aberration assays for assessing of HgCl2- and/or CH3HgCl-induced genotoxicity, and indicated that they are about the same concentration as the 8-OHdG assay. The presence of genotoxic effects in peripheral blood lymphocytes exposed to the mercuric compounds indicated by the chromosome aberrations and the MN assays could be partly due either to the disturbance of the spindle mechanism, or to the elevated level of 8-OHdG brought by the generation of reactive oxygen species.