Effect of different oxidation states of chromium in causing chromosome alterations in cultured CHO cells

Four chromium salts with different oxidation states were tested for their influence in causing chromosome aberrations and sister-chromatid exchange in Chinese hamster ovary cells in vitro. Cell cultures were treated with CrO3, K2Cr2O7, CrCl2 and Cr(NO3)3.9H2O at concentrations of 10(-7), 10(-6), 10(-5) and 10(-4) M for the aberration assay, and 10(-8), 10(-7), 10(-6) and 10(-5) M for the sister-chromatid exchange assay. It was noticed that Cr (VI) compounds--CrO3 and K2Cr2O7--considerably enhanced the frequencies of aberrations and sister-chromatid exchanges compared to the control cultures. CrCl2 and Cr(NO3)3.9H2O--Cr (II) and Cr (III) respectively--caused a slight increase in sister-chromatid exchange rates, but the frequencies of aberrations were almost unchanged compared to the controls. These investigations indicate a definite link between the metals and changes produced in the mammalian chromosomes, reaffirming the evidence of carcinogenic potential of Cr (VI) observed by other investigators.