DNA damage by cadmium and arsenic salts assessed by the single cell gel electrophoresis assay

Human exposure to metals is frequent due to their ubiquity, wide use in ind ustry, and environmental persistence. Direct and indirect genotoxic effects of cadmium (Cd) and arsenic (As) were reported. However, the mechanisms of induction of genetic damage are not well known. The aim of the present wor k was to evaluate the degree of damage induced by Cd and As salts in a huma n lung fibroblasts cell line using the single cell gel electrophoresis assa y (SCGE). MRC-5 cells were treated with cadmium chloride (CdCl2), cadmium sulfate (Cd SO4), sodium arsenite (NaASO(2)) and cacodylic acid (C(2)H(7)ASO(2)). A sig nificant dose-dependent increment in the extent of DNA migration as well as in the percentage of cells with tails was observed (P < 0.001) after treat ment with CdSO4 and NaASO(2). Treatment with CdCl2 induced a relatively low level of DNA strand breaks in comparison with that induced by CdSO4. The i ncrease migration observed with the three compounds could be originated eit her by the direct induction of DNA lesions or by the inhibition of excision repair mechanisms. On the other hand, cells treated with C2H7AsO2 showed a decrease in the migration length with the three doses employed (P < 0.001) . The decrease in the rate of DNA migration could be a consequence of the i nduction of DNA cross-links by organic arsenicals. Cd and As salts induced DNA damage in fibroblast cells, detected as DNA mig ration in the single cell gel (SCG) assay. The distribution of DNA migratio n among cells as a function of dose revealed that the majority of exposed c ells showed more DNA damage than cells obtained from control cultures. The potential for human exposure to both metals has been increased over the yea rs due to the increment in their use. For this reason, elucidation of carci nogenic mechanisms is very important. (C) 2001 Elsevier Science B.V. All ri ghts reserved.