講演情報
[P8-3]プルトニウム被ばく作業員の染色体分析
○穐山 美穂1, 富永 隆子2, 高島 良生1, 栗原 治1, 數藤 由美子1 (1.量子科学技術研究開発機構 放射線医学研究所 計測・線量評価部, 2.量子科学技術研究開発機構 放射線医学研究所 放射線緊急事態対応部)
On June 6, 2017, five workers accidentally inhaled plutonium compounds during their operations to inspect storage container including nuclear materials at a facility of the Japan Atomic Energy Agency. We conducted dicentric chromosome assay (DCA) for the workers in the course of health examinations. They were firstly administered with a chelating agent (Ca-DTPA) before blood sampling. Their estimated doses by DCA were at background levels, suggesting a little possibility of severe whole-body external exposure causing acute radiation syndrome. In 2019, another protocol for biodosimetry, FISH translocation analysis (FISH-tr), was newly developed by International Organization for Standardization (ISO 20046, 2019). The present study applied FISH-tr using three-colored chromosome paints to the the same series of samples for DCA and blood samples from five control donors in order to confirm the effectiveness of this protocol. As a result, the worker's estimated doses were below 0.1 Gy. Age is known to be the major factor that determines the background frequency of translocations. However, the formula for age-adjustment proposed in the ISO standard was unsuccessful in some cases, suggesting a wide interindividual difference in the background translocations. Effect of the smoking habit was also investigated. Two workers showed higher frequency of metaphases having highly bending and twisting chromosomes (2.0-6.1%) than controls (0%) and higher concentration of calcium in blood. Further studies are necessary on the above aging effect for more accurate cytogenetic dose estimation.