Influence of Paternal (252)Cf Neutron Exposure on Abnormal Sperm, Embryonal Lethality, and Liver Tumorigenesis in the F(1) Offspring of Mice

Experiments were conducted to determine whether neutron‐induced genetic damage in parental germline cells can lead to the development of cancer in the offspring. Seven‐week‐old C3H male mice were irradiated with (252)Cf neutrons at a dose of 0, 50, 100, or 200 cGy. Two weeks or 3 months after irradiation, the male mice were mated with virgin 9‐week‐old C57BL females. Two weeks after irradiation, the irradiated male mice showed an increased incidence of sperm abnormalities, which led to embryo lethalities in a dose‐dependent manner when they were mated with unirradiated female mice. Furthermore, liver tumors in male offspring of male mice in the 50 cGy group were significantly increased in 19 of 44 (43.2%) animals, in clear contrast to the unirradiated group (1 of 31; 3.2%) (P < 0.01). In the 100 cGy group, 6 of 39 (15%) mice had lesions. At 3 months after irradiation abnormal sperm and embryonal lethality were not significantly increased. The incidences of liver tumors in male offspring from the 50 cGy, 100 cGy and 200 cGy groups were 6 of 20 (30%), 5 of 22 (23%) and 1 of 19 (5%), respectively, which are not significantly increased compared with the control. It is concluded that increased hepatic tumor risk in the F(1) generation may be caused by genetic transmission of hepatoma‐associated trait(s) induced by (252)Cf neutron irradiation.