Presentation Cytogenetic effects of radionuclide contamination on forest trees around the Fukushima Daiichi nuclear power plant

渡辺, 嘉人  ,  久保田, 善久  ,  府馬, 正一  ,  丸山, 耕一  ,  吉田, 聡

After the accident of the Fukushima Daiichi nuclear power plant, much attention has been focused on the biological consequences of the radionuclides released to the surrounding environment. An effective environmental biomonitoring for genotoxic effects caused by the radiological contamination is the testing of the native field plants for cytogenetic changes in seed meristems, which represent accumulated genetic damage during the seed maturation period. We focused on the seeds of Japanese cedar (Cryptomeria japonica) for studying the cytogenetic changes using a newly improved micronucleus assay system for plants, and compared the micronucleus frequencies in seed meristems with the estimated absorbed dose rates of the seeds.The collection of tree seed samples was carried out every autumn from 2011 to 2013 at 3 sampling locations in the “Area 3” around the power plant, where it is expected that the residents have difficulties in returning for a long time (METI, 2013), as part of a project by the Ministry of the Environment, Japan. Samples were also collected in a low contaminated control location. The absorbed dose rate of the cedar seeds collected in the most contaminated location, approximately 3 km west of the power plant, was estimated to be about 80 µGy/h in November 2011. Even though the absorbed dose rates decreased to around half in 2013, the absorbed dose rate in every sampling location in the “Area 3” still exceeded the criteria dose rate of 4–40 µGy/h selected for pine trees as the “derived consideration reference level” by the ICRP in Publication 108. This suggests the probability of cytogenetic changes in the cedar seeds in the highly contaminated locations. In 2011, the seeds from the trees in the highest contaminated area showed a significantly higher micronucleus frequency in the meristems than those from the trees in the control area. The micronucleus frequency in seed meristems and the estimated absorbed dose rate of the seeds showed a significant positive correlation in the different trees. These results suggest that the micronucleus assay of cedar seeds were effective as an environmental indicator of biological impact of radiation exposure in the radionuclide contaminated areas due to the nuclear accident.
15th International Congress of Radiation Research

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