Which radionuclides contribute most to seafood ingestion dose?

Johansen, M. P.*; Gwynn, J. P.*; Carpenter, J. G.*; Charmasson, S.*; 森 愛理; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*; McGinnity, P.*

Journal of Environmental Radioactivity, 287, p.107706_1 - 107706_8, 2025/07

https://doi.org/10.1016/j.jenvrad.2025.107706

Radiological ingestion doses from eating seafood are regularly evaluated near coastal nuclear facilities, following accidents/events and frequently in national studies worldwide. However, a recent global review found that published seafood doses varied greatly depending on which radionuclides were selected for evaluation and that there has been a tendency to omit important radionuclides or focus on less significant ones. This indicates a need for clear guidance on which radionuclides to prioritise in such studies. Here, we use worldwide data for 16 key radionuclides contributing to typical background seafood ingestion dose. We account for the loss of radionuclides during cooking and the radioactive decay of the short-lived Po. Results indicate that for the typical world consumer, naturally-occurring radionuclides account for 99% of the total seafood ingestion dose, of which about 84% comes from Po and 8% from Pb. About 5% comes from Ra, a far greater proportion than the more frequently-assessed Ra (1%). Other Th- and U-series radionuclides provide far lower contributions (0.07%-0.70%), while C provides about 0.09%. In comparison, the contribution to total seafood ingestion dose from background anthropogenic radionuclides is 1%, with Cs contributing most (0.08%) and Sr, Tc, Ag and Pu adding a further 0.05% together. These percentage contributions to dose can vary somewhat depending on consumption patterns (e.g., differing proportions of fish, bivalves, etc.). However, Po is the dominant contributor irrespective of country-specific diets or restricted diet scenarios (fish-only, seaweed-only, etc.). Study results provide new guidance to improve the design, interpretation and communication of seafood ingestion dose assessments.

Radiological dose from seafood ingestion; A Global summary from 40 years of study

Johansen, M. P.*; Gwynn, J. P.*; Carpenter, J. G.*; Charmasson, S.*; McGinnity, P.*; 森 愛理; Orr, B.*; Simon-Cornu, M.*; Osvath, I.*

Critical Reviews in Environmental Science and Technology, 55(6), p.422 - 445, 2025/00

https://doi.org/10.1080/10643389.2024.2413202

Seafood is an important source for meeting future global nutrient demands. However, it also contributes disproportionately to the radiological ingestion dose of more than five billion world consumers - up to 70%-80% of the total-foods dose in some countries. Although numerous studies report seafood doses in specific populations, there is still no comprehensive evaluation answering basic questions such as "what is the ingestion dose to the average global seafood consumer?" Analysis of 238 worldwide seafood dose estimates suggests that typical adult consumers receive from 0.13 to 0.21 mSv, with a likely best estimate of 0.15 mSv per annual seafood intake. Those consuming large amounts of seafood, particularly bivalves, may experience ingestion doses exceeding 1 mSv per annual intake, surpassing other routine background dose sources. The published studies suggest that doses of 3 mSv or greater are surpassed in about 150 million adult seafood consumers worldwide. Almost all this dose comes from the natural radionuclides that are prevalent in marine systems - especially Po. While trace levels of anthropogenic radionuclides are ubiquitous in seafoods (e.g.,Cs and Pu), the added dose from these is typically orders of magnitude lower. Even following the large-scale releases from the Fukushima accident, with food safety controls in place, the additional dose to consumers in Japan was small relative to routine dose from natural background radionuclides. However, the worldwide seafood dose estimates span seven orders of magnitude, indicating a need for an assessment that integrates global seafood radionuclide data as well as incorporating changes in seafood consumption and production patterns.

中性子照射により生成する鉛・ビスマス合金中のポロニウムの挙動に関する研究, 原子力基礎研究 H10-026 (委託研究)

関本 博*; 井頭 政之*; 矢野 豊彦*; 小原 徹*; 大崎 敏郎*

JAERI-Tech 2002-008, 58 Pages, 2002/03

JAERI-Tech-2002-008.pdf:3.6MB

本研究は、鉛・ビスマス合金の中性子照射によって生成されたポロニウムの生成率(断面積),合金からの放出率及び放出されたポロニウムの各種材料への吸着率を明らかにすることで、鉛・ビスマス冷却高速炉及び加速器駆動未臨界炉でのポロニウムの放出量の定量的評価のための知見を得ることを目的として行われた。ポロニウム生成率については、東工大ペレトロン加速器を用いて高速炉体系で重要なkeV中性子に対するビスマスの断面積を測定した。その結果、中性子捕獲断面積はJENDL評価値の1/2~1/3の値が、ポロニウム生成断面積ではJENDL評価値のほぼ1/3の値を得た。また、中性子照射により生成する鉛ビスマス合金中のポロニウムの挙動に関する実験を行うため、加熱吸着試験装置の設計と動作特性試験及び線測定器の動作特性試験を行い、るつぼやフィルター等の選定やその他の検討を行った。さらに照射設備でのサンプル照射と中性子レベル測定をおこなった。ただし、東工大での実験許可を得るのが遅れたため、鉛・ビスマス合金中のポロニウム挙動に関する実験は今後に残された。

Some studies on the tracer chemistry of polonium

木村 健二郎*; 石森 富太郎

第2回Genova Conf., 28, P. 151, 1958/00

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