Genotoxicity of sodium metabisulfite in mouse tissues evaluated by the comet assay and the micronucleus test.

Sodium metabisulfite (SMB, Na(2)S(2)O(5)) is widely used in the food and pharmaceutical industries, because of its ability to inhibit proliferation of microorganisms and its antioxidant properties. We have evaluated the genotoxic effects of SMB on different tissues of the mouse, by use of the comet assay (liver and blood cells) and the micronucleus test (blood and bone marrow cells). For all tissues, significant increases in damage index and damage frequency values were observed in the SMB-treated groups (1 and 2g/kg doses) compared to the control animals. The Kruskal-Wallis test showed that the mean micronucleus frequencies in peripheral blood and bone marrow cells of mice treated with the highest dose of SMB (2g/kg) showed significant increases, when compared with controls, and a significant reduction in the ratio of polychromatic to normochromatic erythrocytes was also seen. No difference in results between sexes was observed. Our results show that high oral doses of SMB may pose a genotoxic risk.