Tritium RBE estimation based on effects of chronic ingestion of tritiaed water on fetal development of mouse

基于长期摄入氚水对小鼠胚胎发育的影响的氚相对危险度的估计。预期从核燃料后处理厂和未来的核聚变发电厂释放到我们环境中的氚的增加使得估计氚相对危险度很重要，特别是基于慢性氚辐射暴露的长期危害。因此，本研究基于长期摄入氚水对小鼠胚胎发育的抑制作用，尝试测定氚的相对生物效应。在孕期的不同时间，测量胎儿体内的氚浓度，以估算其吸收辐射剂量。氚浓度从妊娠第1天开始逐渐升高，第7天至第9天达到平台期水平。估计的辐射剂量与饮用水中的氚浓度几乎呈线性关系。随着氚辐射剂量的增加，胎儿的体重和脑重量以及脑组织中的蛋白质含量显着减少。将这些氚效应的剂量-效应曲线与~(137)Cs-~(137)Cs-γ射线照射胎儿的剂量-效应曲线进行比较，以估算氚的相对生物效应。由此获得的RBE值落在1.7-1.9的范围内。

Tritium RBE estimation based on effects of chronic ingestion of tritiated water on fetal development of mouse.The anticipated increase in the tritium release into our environment from the nuclear fuel reprocessing plant and the future nuclear fusion power plant makes it important to estimate tritium RBE, especcially on the basis of long-term hazards of chronic tritium radiation exposure. In this study, therefore, an attempt was made to measure the tritium RBE based upon the inhibitory effects of chronically ingested tritiated water on fetal development of mouse.BC3F_1 female mice mated with ICR male were given drinking water containing various concentrations of tritium for whole pregnant period. At various times of the pregnant period, tritium concentration in the fetus was measured to estimate the absorbed radiation dose. The tritium concentration increased gradually from the first pregnent day to reach the plateau level at the 7 to 9th day. The estimated radiation dose increased almost linearly depending on the tritium concentration in the drinking water.The fetal body and brain weight as well as protein content of the brain tissue decreased significantly with increasing radiation dose from tritium. The dose-response curves of these tritium effects were compared with the comparable curves obtained with the chronically ^<137>Cs-gamma-irradiated fetuses, to estimate the tritium RBE. The RBE value thus obtained is fallen within the range of 1.7-1.9.