Glutathion S-transferase positive (GST-P+) hepatic foci development was used as a means of determining whether the offspring of gestating maternal rats, which were subjected to genetically-damaging levels of gamma-ray radiation, were more susceptible to the development of cancer after treatment with diethylnitrosamine (DEN), a known carcinogen. A single dose of 10, 30, 60, and 90 rads involving whole body exposure to gamma-rays was given to pregnant rats at day 14, and during postnatal week 4. DEN was intraperitoneally injected to their offspring twice in one week. Thirteen weeks after birth, the rats were sacrificed. Irradiation of maternal rats with 30 rad gamma-rays before mating significantly increased both the incidence and the size of GST-P+ foci in the livers of both male and female pups, when combined with DEN treatment, whereas other dose levels had no such effect. Using a rat-liver model, the results of this study indicate that a low dose of radiation during the embryonic stage increases the susceptibility to carcinogens. In addition, under certain circumstances low doses of radiation, an externally applied cancer-inducing stimulus, may increase the likelihood of cancer, whereas higher doses may not.

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