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 chro mosome aberrations, and 8-hydroxyde oxyguanosine (8-OHdG) levels to ev aluate the genotoxicity of methyl mercuric chloride (CH3HgCl) and merc uric chloride (HgCl2) in human peripheral lymphocytes. The chromosome aberrations in human peripheral lymphocytes exposed to various concent rations of CH3HgCl or HgCl2 increased in a concentration-dependent man ner 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 in crease 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 pot ent than HgCl2. We determined the 8-OHdG levels in human peripheral bl ood mononuclear cells(PBMC) and found that they were significantly hig her in the exposed groups at 1 X 10(-5) M (HgCl2) and 5 X 10(-6) M (CH 3HgCl) 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 respon se. The data confirmed the value of the MN and/or chromosome aberratio n 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 lymphocy tes exposed to the mercuric compounds indicated by the chromosome aber rations and the MN assays could be partly due either to the disturbanc e of the spindle mechanism, or to the elevated level of 8-OHdG brought by the generation of reactive oxygen species.