Analysis of mutation induction by low dose rate tritium radiation using a hyper- sensitive system

Abstract

An exposure condition of tritium radiation from nuclear fusion reactor could be a long-term exposure at low dose rate. The biological effects of low dose (rate) radiation are not clear because none of suitable detection system has been established. Regarding to mutation induction by high LET radiation such as neutrons, the reversed dose rate effect has been reported when the dose rate is lower than a certain value. On the other hand, it is not clear whether this phenomenon could be seen in the case of tritium radiation. 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. We have tested mutation induction by tritiated water at dose rate between 0.13 and 4.4 cGy/h. Although mutation frequency seems to be slightly increased at lower dose rate tritium radiation, it was not statistically significant. Our results suggest that the reversed dose rate effect may not be seen for mutation induction by tritium radiation.