National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba, Japan.
Fukushima Medical University, 1-Hikarigaoka, Fukushima-city, Fukushima, Japan.
Health Phys. 2021 Aug 1;121(2):133-149. doi: 10.1097/HP.0000000000001429.
More than 9 y have passed since the 2011 nuclear disaster in Fukushima Prefecture, Japan. During this period, much effort has been spent on the dose reconstruction for Fukushima residents; however, the estimation of the internal dose due to the potential intake of the short-lived radionuclides (mainly iodine-131) has been challenging because of the lack of direct human measurements at the early phase of the accident. Our previous study revealed that the residual cesium body contents observed in delayed whole-body counter (WBC) measurements of residents from Namie-town, one of the most affected municipalities, varied greatly with the timepoint of their evacuations on 12 March 2011 when the first explosive event occurred at the accident site; i.e., the late evacuees had much higher residual cesium body contents compared to the prompt evacuees. The present study thus aimed to clarify this finding by reproducing the exposure situation based on the evacuees' personal behavioral data in combination with the latest atmospheric transport and dispersion model (ATDM) simulation for 356 selected subjects in adult and 15-y (13-17 y) age groups. The results demonstrated that the ATDM simulation-based method could reasonably reproduce the subjects' exposure situation, supporting the previous finding. However, the residual cesium-137 body contents calculated by this method were only 10%-20% of those in the subjects' WBC measurements. This large discrepancy was considered to be caused by both the present method's underestimation and the overestimation of the subjects' early intake in the WBC measurements due to a conservative intake scenario not assuming potential additional intake. Additional studies are needed to further clarify the reasons for the discrepancy and to evaluate the magnitude of the inhalation dose in the accident.
自 2011 年日本福岛县核灾难以来，已经过去了 9 年多。在此期间，人们花费了大量精力对福岛居民的剂量进行重建；然而，由于缺乏事故早期的直接人体测量，估算潜在摄入的短寿命放射性核素（主要是碘-131）的内照射剂量具有挑战性。我们之前的研究表明，从福岛县受灾最严重的市之一的女川町撤离的居民延迟全身计数器（WBC）测量中观察到的残留铯体含量，因 2011 年 3 月 12 日事故现场首次爆炸时的撤离时间点而有很大差异；即，晚期撤离者的残留铯体含量比早期撤离者高得多。因此，本研究旨在通过结合最新的大气传输和扩散模型（ATDM）模拟，根据撤离者的个人行为数据，对 356 名成年和 15 岁（13-17 岁）年龄组的选定对象进行重现暴露情况，以阐明这一发现。结果表明，基于 ATDM 模拟的方法可以合理地再现受试者的暴露情况，支持了之前的发现。然而，通过这种方法计算的残留铯-137 体含量仅为 WBC 测量值的 10%-20%。这种巨大差异被认为是由于目前方法对早期摄入量的低估以及 WBC 测量中对受试者早期摄入量的高估，因为保守的摄入情景不假设潜在的额外摄入。需要进一步研究来进一步阐明差异的原因，并评估事故中吸入剂量的大小。
