Transgenerational effects in mice exposed to continuous low dose-rate γ-rays

To study the effects of chronic low dose-rate irradiation with γ-rays on the progeny of mice, males (sires) will be irradiated for 400 days, using 137Cs γ-rays at dose-rates of 20 mGy/day, 1 mGy/day and 0.05 mGy/day with accumulated doses equivalent to 8000 mGy, 400 mGy and 20 mGy, respectively. Immediately after completion of irradiation, the male mice are bred with non-irradiated females to produce F1 mice. Randomly selected F1 males and females will be bred to produce F2 mice. All mice will be kept until their natural death and subjected to pathological examinations upon death. The number of offspring, length of their lifespan and cancer incidence will be compared to those from unirradiated controls for evaluations of the biological effects. Irradiation of the first batch (from a total of 5 batches) consisting of 20 males started in 2004. (author)