Quantitative studies of in vitro morphological transformation of Syrian hamster cells by inorganic metal salts.

Morphological transformation of Syrian hamster embryo cells was induced by direct exposure to some inorganic salts of nickel, cadmium, chromium, beryllium, and arsenic but not salts of iron, titanium, tungstate, zinc, aluminum, and nickel sulfide amorphous. Furthermore, no transfor mation was observed in untreated controls. Lethality, mdi cated by a reduction in cloning efficiency, occurred with carcinogenic and noncarcinogenic metal salts. In addition, transformation of Syrian hamster cells was observed also after transplacental exposure to inorganic salts of nickel, beryllium, chromate, and cadmium which had been injected into pregnant hamsters. The transformed colonies had a variety of morphologies reflecting the cell types present in early passages of cells and were identical to those observed after organic carcinogens. Animal experimental data exist for the carcinogenicity of all positive inorganic metals except arsenic. Epidemiological evidence indicates an as sociation between exposures to all positive metals except for cadmium, although there is a possibility of a relationship betweenoccupational exposuretocadmium and cancerof the prostate. Although in terms of dose-response relation ships cadmium and chromium were the most potent trans forming agents, the comparative potency of the various metals cannot be determined since it would depend on the ionization potential of the metal, the inorganic salt form, and possible biointeractions of the various metals.