Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 71(3): 185-193 (2022)


2019年~2020年に採取した福島県浪江町における自家消費作物中放射性Cs濃度と内部被ばく線量Activity Concentrations of Radiocaesium in Self-consumed Crops Collected in Namie, Fukushima from 2019 to 2020 with Associated Internal Radiation Doses to Humans

1福島大学大学院共生システム理工学研究科Graduate School of Symbiotic Science and Technology, Fukushima University

2福島大学地域未来デザインセンターCommunity Future Design Center, Fukushima University

3長崎大学原爆後障害医療研究所Atomic Bomb Disease Institute, Nagasaki University

4福島大学環境放射能研究所Institute of Environmental Radioactivity, Fukushima University



Present: Kankyo Bunseki Kenkyusho

受付日:2022年4月15日Received: April 15, 2022
受理日:2022年5月23日Accepted: May 23, 2022
発行日:2022年11月15日Published: November 15, 2022

福島県浪江町では東京電力福島第一原子力発電所事故後に除染が行われ,2017年3月31日から居住制限区域及び避難指示解除準備区域が解除された東部で,住民の帰還が始まった。2019年と2020年に除染された圃場とその周辺から,自家栽培作物及び自生植物の様々な自家消費作物を採取した。穀類,いも類,豆類,野菜類及び果実類の181試料の放射性Cs濃度を求め,作物摂取による内部被ばく線量を算出した。自家栽培作物中137Cs濃度は0.18–46 Bq kg−1新鮮重量と,すべて基準値の100 Bq kg−1を下回ったが,圃場周辺の畦や森林から採取した自生植物は栽培作物より高い3.2–175 Bq kg−1新鮮重量であり,一部試料で基準値を超えた。2020年に自家消費作物を摂取した成人男性の放射性Csによる追加となる内部被ばく線量は0.032 mSvであり,事故により追加となる内部及び外部被ばく線量0.64 mSvの約5%を占めた。自生植物を含めず自家栽培作物のみを摂取した場合の内部被ばく線量は0.012 mSvとなり,自生植物も含む自家消費作物を摂取した場合の約1/3であり,1 mSvを十分に下回った。

In Namie Town, Fukushima Prefecture, decontamination was carried out after the Fukushima Daiichi Nuclear Power Station accident. After remediation, the restricted residential area and the area preparing for the lifting of evacuation orders in the eastern part of Namie Town were lifted, and residents started returning home beginning on March 31, 2017. Various self-consumed crops, including homegrown agricultural crops and edible wild plants, were collected from the decontaminated fields and surrounding areas in 2019 and 2020. Activity concentrations of radiocaesium were measured in 181 samples of grain, potatoes, beans, vegetables, and fruits. Internal radiation exposure to humans from ingestion of the crops were calculated. Activity concentrations of 137Cs in the homegrown agricultural crops ranged from 0.18 to 46 Bq kg−1 fresh weight, which were all below the standard limit of 100 Bq kg−1, while in the wild plants collected from around the fields 137Cs ranged from 3.2 to 175 Bq kg−1 fresh weight. The additional internal radiocaesium radiation dose for adult males in 2020 from ingestion of the various self-consumed crops was 0.032 mSv, accounting for approximately 5% of the total additional internal and external radiation dose of 0.64 mSv due to the accident. The internal radiation dose from the intake of the homegrown agricultural crops, excluding wild plants, was 0.012 mSv, which was about 1/3 of that from the intake of both self-consumed crops and wild plants, and well below 1 mSv.

Key words: decontaminated field; homegrown agricultural crops; edible wild plants; radiocaesium; additional radiation exposure

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