Lang S, Raunemaa T
Department of Environmental Health, University of Kuopio, Finland.
Radiat Res. 1991 Jun;126(3):273-9.
The behavior of neutron-irradiated, simulated Chernobyl UO2 particles containing 141Ce, 144Ce, 95Zr, 95Nb, and 103Ru in the gastrointestinal tract was investigated to obtain basic information for dosimetric and risk analyses of nuclear accidents. After the UO2 particles were administered to rats intragastrically, the distribution and retention of specific radionuclides were studied by using whole-body autoradiography and gamma-spectrometric analysis of tissues. None of the radionuclides were detected in liver, kidney, muscle, bone, brain, blood, and urine. Approximately 98% of the total administered radioactivity was excreted in feces within 3 days. A two times greater intestinal retention (about 6%) of 95Nb than for the other radionuclides was observed 1 day after administration. The results indicate that this kind of relatively insoluble particulate material is not absorbed or retained significantly in the epithelial cells of the intestinal wall. Fallout particles containing high-energy beta sources, 106Ru and 144Ce, result in a very high radiation dose (up to several Gy/day) in the vicinity of a hot particle. Niobium-95 with low average beta energy (0.043 MeV (100%)) does not increase the total dose to the GI tract significantly despite its longer retention in the intestine. Evaluation of the biological effects of these particles in the GI tract by using a dosimetric model based on uniform distribution of activity may be misleading.
为获取核事故剂量学和风险分析的基础信息，对含有¹⁴¹Ce、¹⁴⁴Ce、⁹⁵Zr、⁹⁵Nb和¹⁰³Ru的中子辐照模拟切尔诺贝利UO₂颗粒在胃肠道中的行为进行了研究。将UO₂颗粒经胃内给予大鼠后，通过全身放射自显影和组织的γ能谱分析研究了特定放射性核素的分布和滞留情况。在肝脏、肾脏、肌肉、骨骼、大脑、血液和尿液中均未检测到任何放射性核素。给药后3天内，约98%的总给药放射性活度经粪便排出。给药1天后，观察到⁹⁵Nb在肠道中的滞留量比其他放射性核素高两倍（约6%）。结果表明，这种相对不溶性的颗粒物质在肠壁上皮细胞中不会被显著吸收或滞留。含有高能β源¹⁰⁶Ru和¹⁴⁴Ce的沉降颗粒在热颗粒附近会导致非常高的辐射剂量（高达数Gy/天）。平均β能量较低（0.043 MeV（100%））的⁹⁵Nb尽管在肠道中滞留时间较长，但不会显著增加胃肠道的总剂量。使用基于活度均匀分布的剂量学模型评估这些颗粒在胃肠道中的生物学效应可能会产生误导。
