Transgenerational effects of radiation

Transgenerational effects of radiation are often observed in experimental studies using animals. It has been reported in mega-mouse experiments that the germ cells of irradiated individuals have an increased mutation rate, and that the radiation-induced mutation rate is higher when the dose rate is higher than when it is lower. In humans, an early study on the children of A-bomb survivors found no effects on birth malformations, neonatal deaths, stillbirths, or sex ratios. A survey of approximately 41,000 children born to A-bomb survivors between 1946 and 1984 found no increase in cancer and non-cancer mortality up to 1999 compared with the controls. It is not fully understood why the effects of transgenerational effects are not observed in humans. Even if radiation-induced transgenerational effects have occurred in humans, they are considered to be very small compared with the frequency of spontaneous onset and are not easy to detect. (A.O.)