Tumorigenicity of nickel subsulfide in Strain A/J mice

The pulmonary tumor response of Strain A mice has been reported to be a rapid and efficient predictor of carcinogenic potential for a variety of chemicals. The route of exposure has usually been by intraperitoneal injection (i.p.) of solubilized materials. We compared intratracheal (i.t.) instillation as a more representative route typical of human exposures, with i.p. injection of nickel subsulfide, a potent animal carcinogen. Animals were sacrificed either 20 weeks after the first dosing, or were held until 45 weeks after the first dosing. Urethane, a positive control, produced a significant increase in pulmonary tumor response after i.t. instillation as well as i.p. injection. For nickel subsulfide treated animals, there was no evidence of a dose-related increase in pulmonary tumor response in any i.p. or i.t. treatment group when compared with age-matched controls.