Research Institute of Science for Safety and Sustainability (RISS), National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3Aramaki-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
Environ Int. 2018 May;114:107-114. doi: 10.1016/j.envint.2018.02.015. Epub 2018 Feb 28.
Outdoor decontamination efforts have been ongoing since the Fukushima Daiichi nuclear power plant (FDNPP) accident; however, little is known about indoor contamination. Therefore, house dust was sampled based on particle size in 21 wooden buildings (19 residential houses and 2 community centers) within the evacuation area close to the FDNPP, Fukushima Prefecture, Japan. Activities of radiocesium (Cs) per gram of house dust increased with decreasing particle size (mean: 6.1 × 10, 2.6 × 10, 1.6 × 10, 7.5 × 10, 5.0 × 10, and 4.6 × 10 Bq/g for <4-20, 20-63, 63-180, 180-500, 500-1000, and 1000-2000 μm, respectively). The Cs concentrations in house dust were inversely related to the square of distance from the FDNPP for <4-1000 μm particles. From the results of the multiple linear regression analysis, distance from the FDNPP and direction from the FDNPP (northwest) were significantly related to the radioactivity of house dust. It was found that 19%, 33%, and 48% of Cs in house dust were extracted in water, 1 M HCl, and not extracted, respectively. Considering the bioaccessibility and assuming a 20 mg/day daily intake of house dust, the daily doses would be 7.2 Bq/day (mean) and 18 Bq/day (95th percent quantile). These results provide valuable insight into indoor radioactive Cs contamination in the area around the FDNPP and possible oral exposure to indoor radioactive Cs after returning home.
自福岛第一核电站（FDNPP）事故以来，一直在进行户外去污工作；然而，对于室内污染知之甚少。因此，在日本福岛县 FDNPP 附近的撤离区，基于粒径对 21 座木质建筑物（19 座住宅和 2 个社区中心）中的房屋灰尘进行了采样。每克房屋灰尘中的放射性铯（Cs）活度随粒径的减小而增加（平均值：<4-20μm 粒径的 6.1×10、2.6×10、1.6×10、7.5×10、5.0×10 和 4.6×10 Bq/g；20-63μm 粒径的 2.6×10、1.6×10、7.5×10、5.0×10、4.6×10 和 3.9×10 Bq/g；63-180μm 粒径的 1.6×10、7.5×10、5.0×10、4.6×10、3.9×10 和 3.3×10 Bq/g；180-500μm 粒径的 7.5×10、5.0×10、4.6×10、3.9×10、3.3×10 和 2.6×10 Bq/g；500-1000μm 粒径的 5.0×10、4.6×10、3.9×10、3.3×10、2.6×10 和 1.6×10 Bq/g；1000-2000μm 粒径的 4.6×10、3.9×10、3.3×10、2.6×10 和 1.6×10 Bq/g）。房屋灰尘中的 Cs 浓度与距 FDNPP 的距离的平方呈反比，粒径小于 4-1000μm。从多元线性回归分析的结果来看，距 FDNPP 的距离和距 FDNPP 的方向（西北）与房屋灰尘的放射性显著相关。结果发现，水中可提取、1M HCl 可提取和不可提取的房屋灰尘中分别有 19%、33%和 48%的 Cs。考虑到生物可利用性，并假设每天摄入 20mg 的房屋灰尘，每天的剂量将分别为 7.2 Bq/天（平均值）和 18 Bq/天（95%分位数）。这些结果为 FDNPP 周围地区室内放射性 Cs 污染以及回家后可能通过口服摄入室内放射性 Cs 提供了有价值的见解。
