Antiproliferative and genotoxic effects of chromium on cultured mammalian cells

Potassium dichromate [Cr(VI), hexavalent chromium] and chromic chloride [Cr(III), trivalent chromium] were added to tissue cultures of Chinese hamster ovary (CHO) cells. Cr(III) at 10 μM did not significantly affect cell proliferation. On the other hand, 10 and 1 μM Cr(VI) inhibited cell proliferation, while 0.1 μM did not. Addition of ascorbic acid (50 μg/ml), for periods up to 6 h after Cr(VI), effectively reversed the antiproliferative effects of Cr(VI). Several sulfhydryl‐containing agents, under similar conditions, were ineffective. Cr(III) at 10 μM did not induce sister chromatid exchanges (SCEs) in cultured CHO cells. On the other hand, Cr(VI) did; there was a dose‐response in the SCE induction by Cr(VI) between 0.01 and 1 μM Cr(VI). Addition of ascorbic acid, for periods up to 4 h after Cr(VI), reversed Cr(VI)‐induced SCEs. We suggest that the genotoxic effects of Cr(VI) (i.e., SCE induction) may be causally related to the antiproliferative effects that we observed.