Abstract
Tritium radiation from nuclear fusion reactor is expected to be a long-term and a low dose rate exposure. The biological effects of low dose (rate) radiation are still unclear because there are many reports on the!unexpected phenomenon' induced by low dose-rate radiation. For example, the reversed dose rate effect has been reported regarding to mutation induction by high LET radiation such as neutrons. We are doing experiments to clarify whether this phenomenon could be seen in the case of tritium radiation or not. To examine the low dose rate effect of tritium radiation, we established a hypersensitive mutation detection system using hamster cells carrying a human X-chromosome. The mutation induction by tritiated water at dose rate between 0.13 and 2.3 cGy/h. has been tested and found no statistic significance on the mutation frequency among the tested dose rates. The mutation spectrum in the tritium-induced mutants became to be similar to those in somatic mutation. These results suggest that the reversed dose rate effect might not be seen for somatic mutation induction by tritium radiation, and that mutation by low-dose rate tritium might be induced by a similar mechanism as spontaneous mutation.
