Review of genetic effects and mechanisms of action of chromium compounds.

When similar experimental conditions are adopted to test Cr(VI) and Cr(III) genotoxicity, only the former gives positive results, and Cr(III) is scored as genetically inert. Since Cr(III) seems to be the main final genotoxic agent inside the cell, the observed difference in genetic activity of the two oxidation states can be referred to the easy transport of Cr(VI) across the plasma membrane, as opposed to the lack of membrane carriers for Cr(III). If the experimental design is adjusted to Cr(III) properties, Cr(III) appears (mildly) genotoxic. The accepted inactivity of Cr(III) on whole cells is thus questionable and the environmental impact of Cr(III) accumulation is worth reconsidering.