Comparisons of carcinogenicities of nickel compounds in rats.

This study demonstrates marked differences in the incidences of sarcomas in Fischer rats within 2 years after a single im injection of 4 insoluble nickel-containing powders: amorphous nickel monosulfide (NiS), nickel subsulfide (alphaNi3S2), partially converted nickel-iron sulfide matte, and metallic nickel. The powders (less than 2 um median particle diameters) were administered in penicillin suspension, and each powder was tested at 2 dosages. Whereas alphaNi3S2 was highly carcinogenic, amorphous NiS did not induce any tumors. The carcinogenic potency of partially converted nickel-iron sulfide matte was less than alphaNi3S2 but greater than Ni powder. No sarcomas occurred at the injection site in two groups of control rats that received im injections of penicillin or Fe powder. The observed differences in carcinogenic potencies of alphaNi3S2 and amorphous NiS may provide an experimental approach to elucidate the molecular mechanisms of nickel carcinogenesis.