Sister chromatid exchanges in Chinese hamster V79 cells treated with the trivalent chromium compounds chromic chloride and chromic oxide

Abstract

The induction of sister chromatid exchanges (SCEs) in Chinese hamster V79 cells exposed to soluble CrCl₃ and insoluble Cr₂O₃, compounds of trivalent chromium (Cr³⁺), was determined. Their ability to induce SCEs was compared with those of three hexavalent chromium (Cr⁶⁺) compounds: K₂CrO₄, Na₂CrO₄ and Na₂Cr₂O₇. Both the delay in progression through the cell cycle induced by Cr³⁺ compounds and the SCE frequencies in the delayed cells were also evaluated. The exposure for 28 h to CrCl₃ and Cr₂O₃ at concentrations of 9.7–39 μg and of 34–136 fig of Cr³⁺ per ml, respectively, induced a statistically significant (p < 0.001) dose-dependent increase in SCEs up to 1.9–fold (CrCl₃ and 4-fold (Cr₂Cl₃) over control levels. Compared with the effective concentrations of Cr⁶⁺ compounds, which produced up to 4-fold increase of SCEs, inducing concentrations of CrCl₃ and Cr₂O₃ were 300- and 1000-fold higher in terms of chromium. By prolongation of treatment time up to 48 h, a progressive dose- and time-related enhancement in SCE frequencies induced by Cr³⁺ compounds in delayed cells was observed. Lower concentrations of Cr₂O₃, without effect after 28 h of treatment, induced an increase of SCEs by prolongation of exposure time.