Estimation of internal exposure of the thyroid to 131I on the basis of 134Cs accumulated in the body among evacuees of the Fukushima Daiichi Nuclear Power Station accident

• Published in: Environment international Vol. 61; pp. 73 - 76
• Main Authors: Hosoda, Masahiro, Tokonami, Shinji, Akiba, Suminori, Kurihara, Osamu, Sorimachi, Atsuyuki, Ishikawa, Tetsuo, Momose, Takumaro, Nakano, Takashi, Mariya, Yasushi, Kashiwakura, Ikuo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2013; Elsevier
• Subjects: 131I/134Cs activity ratio; Applied sciences; Biological and medical sciences; Biological effects of radiation; Energy; Environment. Living conditions; Exact sciences and technology; Fukushima nuclear accident; Fundamental and applied biological sciences. Psychology; General, economic and professional studies; Medical sciences; Public health. Hygiene; Public health. Hygiene-occupational medicine; Radiocontamination; Radioiodine; Staff. Occupational work. Work management. Control. Safety. Accidents. Professional diseases; Thyroid dose assessment; Tissues, organs and organisms biophysics; Uptake factor; Whole body counting; Asia; Japan; Radioiodine; Whole body counting; Fukushima nuclear accident; 131I/134Cs activity ratio; Thyroid dose assessment; Uptake factor; Human; Measurement; Estimation; Radioactive contamination; Exposure; Thyroid gland; Radioisotope; l; Uptake; Nuclear accident; Nuclear power plant; Cs activity ratio; Fukushima nuclear power plant accident; Nuclear explosion; Whole body; Dose; Counting; Radioactivity
• ISSN: 0160-4120; 1873-6750
• DOI: 10.1016/j.envint.2013.09.013

Namie Town was heavily contaminated by the Fukushima Daiichi Nuclear Power Station accident. The thyroid equivalent dose for residents who lived in Namie was estimated using results of whole body counting examinations which were carried out by the Japan Atomic Energy Agency a few months after the nuclear accident. Photon peaks of 131I and 134Cs were previously measured by the authors using a NaI(Tl) scintillation spectrometer and that information was used to estimate the 131I/134Cs activity ratio of total intake in the present study. The maximum values of 131I/134Cs activity ratio corresponding to thyroid uptake factors of 0.3, 0.1 and 0.03 were evaluated to be 0.9, 2.6 and 8.7, respectively. The maximum value of the 131I/134Cs activity ratio was used to obtain the most conservative thyroid equivalent dose estimation. The maximum internal exposure of the thyroid to 131I on the basis of 134Cs accumulated in the body measured by the whole body counter was estimated to be 18mSv. This value was much smaller than 50mSv that the International Atomic Energy Agency recommends as the dose at which exposed persons should take stable iodine tablets. •The thyroid dose was estimated using the results of whole body counting examinations.•131I/134Cs ratio was estimated using the results obtained by direct measurements.•131I/134Cs ratio changed significantly depending on the thyroid uptake factor.•The maximum thyroid equivalent dose of 18mSv was obtained for one child.