Cytotoxic, mutagenic and clastogenic effects of industrial chromium compounds

Ten Cr(III) compounds, used in the leather tanning industry,and a Cr(III) compound, containing chromite and used as a pigment,were tested for cytotoxicity (inhibition of growth and survivalof cultured hamster cells), mutagenicity (point mutations inS. typhimurium) and dastogenic activity (chromosomal aberrationsand sister chromatid exchanges in hamster cells). ReferenceCr compounds were potassium dichromate as Cr(VI), and chromiumchloride and two different preparations of chromium nitrateas Cr(III). A contamination with Cr(VI) was detected in someof the Cr(III) tannins, chromite and one chromium nitrate. Cr(III)compounds were cytotoxic at concentrations of Cr(III) 100–500times higher than Cr(VI), but contaminated Cr(III) compoundsshowed a significant cytotoxicity. Reference Cr(VI) but notCr(III) was mutagenic: of the contaminated compounds only chromiteand chromium nitrate, which contained higher levels of Cr(VI),were found to be mutagenic. The frequency of sister chromatidexchanges was significantly increased only by Cr(VI) and themore contaminated Cr(III) compounds. However, an increase ofchromosomal aberrations was produced also by reference Cr(III)salts and the weakly contaminated industrial Cr(III) compounds.These results confirm the view that the active mutagenic agentin intact cell systems is Cr(VI), but indicate that industrialCr(III) compounds cannot be considered genetically inert, asthey can be contaminated by Cr(VI) and induce chromosomal aberrations.