Comparative Inhalation Toxicity of Nickel Sulfate to F344/N Rats and B6C3F1 Mice Exposed for Twelve Days

Comparative Inhalation Toxicity of Nickel Sulfate to F344/NRats and B6C3F₁ Mice Exposed for Twelve Days. BENSON, J. M.,BURT, D. G., CARPENTER, R. L., EIDSON, A. F., HAHN, F. F., HALEY,P. J., HANSON, R. L., HOBBS, C. H., PICKRELL, J. A., AND DUNNICK,J. K. (1988). Fundam. Appl. Toxicol 10, 164-178. Groups of F344/Nrats and B6C3F, mice were exposed to aerosols of nickel sulfatehexahydrate (NiSO₄-6H₂O) 6 hr/day for 12 days to determine theshort-term inhalation toxicity of this compound. Target exposureconcentrations were 60, 30, 15, 7, 3.5, and 0 mg NiSO₄.6H₂O/m³.Endpoints evaluated included clinical signs, mortality, quantitiesof Ni in selected tissues, effect on mouse resistance to tumorcells, and pathological changes in tissues of both rats andmice. All mice exposed to 7 mg NiSO₄ 6H2O/m³ or greater and10 rats exposed to 15 mg NiSO₄ 6H2O/m³ or greater died beforethe termination of exposures. Quantities of Ni remaining inlungs of rats at the end of the exposure were independent ofexposure concentration. Lung burdens of Ni in mice were approximatelyone-half that in lungs of rats. Exposure of female mice to 3.5mg NiSO₄ 6H2O/m³had no effect on resistance to tumor cells asdetermined by spleen natural killer cell activity. Histopathologicalchanges were seen in tissues of rats and mice exposed to aslow as 3.5 mg NiSO₄ 6H2O/m³. Lesions related to NiSO₄ 6H2O/m³exposureoccurred in lung, nose, and bronchial and mediastinal lymphnodes. Results indicated that exposure of rats and mice to amountsof NiSO₄ 6H2O/m³aerosols resulting in Ni exposure concentrationsonly eight times greater than the current threshold limit valuefor soluble Ni (0.1 mg/m³) for as little as 12 days can causesignificant lesions of the.