Bioassay of environmental nickel dusts in a particle feeding ciliate.

The ciliated protozoan Paramecium was used to quantitate cytotoxic and genotoxic effects of nickel particles. The biological response of these eukaryotic cells to pure nickel powder and iron-nickel powder was assayed and compared to the effect of the inorganic carcinogen nickel subsulfide. Cytotoxicity was determined by the percent survival of treated cells. Genotoxicity was indicated by significant increases in the fraction of nonviable offspring (presumed index of lethal mutations) found after self-fertilization (autogamy) in parents from the nickel-treated versus neutral control groups. The cells were exposed to the dusts and the biological effects determined. Only the nickel subsulfide consistently showed a significant increase in offspring lethality.