A comparison of the mutagenicity of soluble trivalent chromium compounds with that of potassium chromate.

The mutagenic potential of water soluble complexes of trivalent chromium with five different amino acids in Salmonella typhimurium strains TA92, TA94, TA98, and TA100 was studied. All complexes were nonmutagenic at concentrations up to 50 mumol/plate in the strains used. In contrast, trivalent chromium chloride was slightly mutagenic in TA98 and a considerable increase in numbers of revertants was observed in TA94. Hexavalent chromium was nonmutagenic in TA98. Strong mutagenic effects were found in TA92, TA94, and TA100. The large difference in mutagenicity between trivalent and hexavalent chromium is discussed with respect to affinity to extracellular phosphate, diffusability through membranes and reactivity with DNA. More definitive statements about the toxicological risks of the water soluble chromium complexes requires additional studies with well defined compounds in test systems specially suited to study metal complexes.