ASSESSMENT OF BIOLOGICAL EFFECT OF TRITIATED WATER BY USING HYPERSENSITIVE SYSTEM
ASSESSMENT OF BIOLOGICAL EFFECT OF TRITIATED WATER BY USING HYPERSENSITIVE SYSTEM
复制标题
DOI：
10.13182/fst11-a12624
复制
发表时间：
2011-10-01
影响因子：
0.9
通讯作者：
Tachibana, Akira
中科院分区：
文献类型：
--
作者：
Tauchi, Hiroshi;Imamura, Hiroto;Tachibana, Akira
核聚变反应堆的氚辐射对人或动物的照射是低剂量和低剂量率的。我们的重点是氚水（HTO）在低剂量和/或低剂量率的生物效应。建立了用于体外培养的哺乳动物细胞或转基因小鼠辐射生物学实验的超敏检测系统，并对其用于评价HTO生物效应的可行性进行了检验。用携带人X染色体的仓鼠细胞建立了Hprt基因突变的超灵敏检测系统。该细胞对Hprt缺陷突变的敏感性超过50倍，这使我们能够检测到剂量低于0.2戈伊的辐射引起的突变频率的显著升高。由于已经报道了中子等高LET辐射诱导突变的反向剂量率效应，我们首先测试了HTO（氚β射线）是否可以看到反向剂量率效应。在0.05 cGy/h和2.0 cGy/h之间的剂量率范围内，观察到HTO的突变频率无显著变化，而在裂变中子或碳束的情况下观察到明显的反向剂量率效应。结果表明，反向剂量率效应不适用于HTO诱发突变的情况。此外，HTO诱导的突变体的突变谱与自发诱导的突变体相似，表明一定水平的HTO暴露可以增强自发突变。
An exposure of human or animals to tritium radiation from nuclear fusion reactor is expected to be a low dose and with low dose-rate. We are focusing on the biological effects of tritiated water (HTO) given at low dose and/or with low dose rate. Hypersensitive assay systems for radiation biological experiments using cultured mammalian cells or transgenic mice have been established and their availability for assessment of biological effects of HTO were tested. A hypersensitive detection system for mutagenesis at Hprt locus was established by using hamster cells carrying a human X-chromosome. The cells present more than 50-fold sensitivity for Hprt-deficient mutation, and this allowed us to detect a significant elevation of mutation frequency by radiations at the dose of less than 0.2 Gy.Because the reverse dose rate effect has been reported for mutation induction by high LET radiation such as neutrons, we first tested whether the reverse dose rate effects could be seen for HTO (tritium beta-rays) or not. No significant change in mutation frequency by HTO was observed in the range of dose rates between 0.05 cGy/h and 2.0 cGy/h, whereas clear reverse dose rate effects was observed in the case of fission neutrons or carbon beam. The result suggests that the reverse dose rate effect does not apply in the case of mutation induction by HTO. In addition, mutation spectrum in the mutants induced by HTO was similar to those in spontaneously induced mutants, suggesting that exposure to a certain level of HTO could enhance the spontaneous mutagenesis.