Negative test for transplacental carcinogenicity of nickel subsulfide in Fischer rats.

Transplacental carcinogenicity of nickel subsulfide (Ni3S2) was tested by im administration of Ni3S2 (20 mg) to 8 pregnant Fischer rats on day 6 of gestation. Control dams received a similar injection of the vehicle. The progeny at risk for tumor development comprised 50 offspring (17 males, 33 females) of Ni3S2-treated dams and 53 offspring (29 males, 24 females) of control dams. Body weights of progeny of Ni3S2 treated dams were lower than progeny of control dams, but sex-specific cumulative mortality rates in the two groups did not differ significantly. By age 26 months, 2 malignant and 2 benign tumors developed in progeny of Ni3S2-treated dams, versus 3 malignant and 2 benign tumors in progeny of control dams. Hence, administration of Ni3S2 to pregnant rats had no significant effect upon tumor incidence in the progeny.