Toxicity and transformation potency of nickel compounds in BHK cells in vitro

An in vitro bioassay utilizing BHK-21 cells in culture was used to determine the relative transformation potency of nickel metal and a number of nickel compounds. These included as relatively insoluble particulates a known carcinogen, nickel subsulfide (Ni3S2) and several oxides either of commercial interest or found in the working environment in the metal industry [e.g., nickel oxide (NiO)], and a soluble salt, nickel acetate [Ni(CH3COO)2]. Although a wide range of transformation potency was found as a function of the dose of nickel per area of culture, all substances produced the same number of transformed colonies at the same degree of toxicity (e.g., 50% survival). Toxicity may arise from nickel originating in membrane-bound or phagocytized particles, or nickel available from solution. If toxicity is a direct measure of net available nickel, then apparently nickel or nickel ion per se is the ultimate transforming agent, independent of source or uptake mechanism.