National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan.
Health Phys. 2021 Apr 1;120(4):387-399. doi: 10.1097/HP.0000000000001345.
It is very important to determine the precise internal thyroid doses of Fukushima residents involved in the 2011 Fukushima nuclear disaster, particularly for small children. This has been challenging due to the lack of direct human measurements to identify 131I, the biggest contributor to the thyroid doses. We previously used a dataset of late whole-body counter (WBC) measurements targeting 134Cs and 137Cs for the thyroid dose estimation in comparison with the intake ratios of 131I to 137Cs (or 134Cs) derived from thyroid and whole-body doses individually obtained from different subject groups, assuming simultaneous acute intake via inhalation. Herein, we applied the same method to the doses of residents in Iwaki city (located south of the Fukushima Daiichi Nuclear Power Plant) with a relatively high activity ratio (131I/137Cs) for the ground deposition density. Our analyses revealed that the intake ratio (131I/137Cs) for the Iwaki residents was 4.2-4.3, which is relatively consistent with the values obtained in other studies (average 3.0-5.0). No regional difference in the intake ratios from other areas was observed, but further studies are required to determine the accurate intake ratio in the early phase of the accident, in particular focusing on the reasonable interpretation of results of the late WBC measurements to evaluate the actual Cs intake.
确定 2011 年福岛核灾难中涉事福岛居民的准确体内甲状腺剂量非常重要，尤其是对于儿童而言。由于缺乏直接的人体测量来确定 131I，这给甲状腺剂量的确定带来了挑战，131I 是导致甲状腺剂量的最大因素。我们之前曾使用针对 134Cs 和 137Cs 的晚期全身计数器 (WBC) 测量数据集，通过与单独从不同对象组获得的甲状腺和全身剂量中得出的 131I 与 137Cs（或 134Cs）的摄取比进行比较，来估算甲状腺剂量，假设是通过吸入同时摄入。在此，我们将相同的方法应用于位于福岛第一核电站以南的磐城市（Iwaki city）居民的剂量，其地面沉积密度的活性比（131I/137Cs）相对较高。我们的分析表明，磐城居民的摄取比（131I/137Cs）为 4.2-4.3，这与其他研究的结果（平均 3.0-5.0）相对一致。未观察到其他地区摄取比的区域差异，但需要进一步研究以确定事故早期的准确摄取比，特别是要关注对晚期 WBC 测量结果的合理解释，以评估实际 Cs 摄取量。
