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Suzuki G, Ishikawa T, Ohba T, Hasegawa A, Nagai H, Miyatake H, Yoshizawa N. Estimation of children's thyroid equivalent doses in 16 municipalities after the Fukushima Daiichi Nuclear Power Station accident. JOURNAL OF RADIATION RESEARCH 2022; 63:796-804. [PMID: 36109336 PMCID: PMC9726711 DOI: 10.1093/jrr/rrac058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/26/2022] [Indexed: 06/15/2023]
Abstract
To elucidate the association between radiation dose and thyroid cancer after the 2011 Fukushima Daiichi Nuclear Power Station (FDNPS) accident, it is essential to estimate individual thyroid equivalent doses (TEDs) to children. In a previous study, we reported a methodology for reconstructing TEDs from inhalation. That methodology was based on individual behavioral survey sheets of the Fukushima Health Management Survey (FHMS) combined with a spatiotemporal radionuclides database constructed by an atmospheric transport, diffusion, and deposition model (ATDM)-the Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI) in seven municipalities. In the present study, we further refined our methodology and estimated the combined TEDs from inhalation and ingestion among children in 16 municipalities around the nuclear power station utilizing 3256 individual whereabouts questionnaire survey sheets. Distributions of estimated TEDs were similar to estimates based on direct thyroid measurements in 1080 children in Iwaki City, Kawamata Town, Iitate Village, and Minamisoma City. Mean TEDs in 1-year-old children ranged from 1.3 mSv in Date City to 14.9 mSv in Odaka Ward in Minamisoma City, and the 95th percentiles varied from 2.3 mSv in Date City to 28.8 mSv in Namie Town. In the future, this methodology can be useful for the epidemiological studies of thyroid cancer after the FDNPS accident.
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Affiliation(s)
- Gen Suzuki
- Correspondence author: Kitakanemaru, Ohtawara City, Tochigi Prefecture, 324-8501, Japan. , Tel: +81-0287-24-1001, FAX: +81-0287-24-1003)
| | - Tetsuo Ishikawa
- Radiation Medical Science Centre for the Fukushima Health Management Survey, Fukushima Medical University, Fukushima 960-1247, Japan
- Department of Radiation Physics and Chemistry, School of Medicine, Fukushima Medical University, Fukushima 960-1247, Japan
| | - Takashi Ohba
- Department of Radiation Health Management, School of Medicine, Fukushima Medical University, Fukushima 960-1247, Japan
| | - Arifumi Hasegawa
- Department of Radiation Disaster Medicine, School of Medicine, Fukushima Medical University, Fukushima 960-1247, Japan
| | - Haruyasu Nagai
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Hirokazu Miyatake
- Societal Safety and Industrial Innovation Division, Mitsubishi Research Institute, Inc., Tokyo 100-8141, Japan
| | - Nobuaki Yoshizawa
- Societal Safety and Industrial Innovation Division, Mitsubishi Research Institute, Inc., Tokyo 100-8141, Japan
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Kim E, Yajima K, Igarashi Y, Tani K, Hashimoto S, Nakano T, Akashi M, Kurihara O. Intake Ratio of 131I to 137CS Derived from Thyroid and Whole-body Doses to Residents of Iwaki City in Japan's Fukushima Prefecture. HEALTH PHYSICS 2021; 120:387-399. [PMID: 33229943 DOI: 10.1097/hp.0000000000001345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
ABSTRACT It is very important to determine the precise internal thyroid doses of Fukushima residents involved in the 2011 Fukushima nuclear disaster, particularly for small children. This has been challenging due to the lack of direct human measurements to identify 131I, the biggest contributor to the thyroid doses. We previously used a dataset of late whole-body counter (WBC) measurements targeting 134Cs and 137Cs for the thyroid dose estimation in comparison with the intake ratios of 131I to 137Cs (or 134Cs) derived from thyroid and whole-body doses individually obtained from different subject groups, assuming simultaneous acute intake via inhalation. Herein, we applied the same method to the doses of residents in Iwaki city (located south of the Fukushima Daiichi Nuclear Power Plant) with a relatively high activity ratio (131I/137Cs) for the ground deposition density. Our analyses revealed that the intake ratio (131I/137Cs) for the Iwaki residents was 4.2-4.3, which is relatively consistent with the values obtained in other studies (average 3.0-5.0). No regional difference in the intake ratios from other areas was observed, but further studies are required to determine the accurate intake ratio in the early phase of the accident, in particular focusing on the reasonable interpretation of results of the late WBC measurements to evaluate the actual Cs intake.
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Affiliation(s)
- Eunjoo Kim
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan
| | - Kazuaki Yajima
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan
| | | | - Kotaro Tani
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan
| | - Shozo Hashimoto
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan
| | - Takashi Nakano
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan
| | | | - Osamu Kurihara
- National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-city, Chiba 263-8555, Japan
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Takagi M, Ohara T, Goto D, Morino Y, Uchida J, Sekiyama TT, Nakayama SF, Ebihara M, Oura Y, Nakajima T, Tsuruta H, Moriguchi Y. Reassessment of early 131I inhalation doses by the Fukushima nuclear accident based on atmospheric 137Cs and 131I/ 137Cs observation data and multi-ensemble of atmospheric transport and deposition models. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 218:106233. [PMID: 32421570 DOI: 10.1016/j.jenvrad.2020.106233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/08/2020] [Accepted: 03/02/2020] [Indexed: 06/11/2023]
Abstract
The Fukushima Dai-ichi Nuclear Power Plant accidents following the March 11, 2011 Tohoku earthquake, and subsequent tsunami released radioactive materials into the atmosphere and caused significant public health concerns, particularly thyroid cancers in children. However, the lack of measurement data for atmospheric concentrations of 131I has caused persistent and widespread uncertainty. This study estimated the maximum potential thyroid doses of inhaled 131I in the early post-accident phase between March 12 and 23, 2011 by using the hourly measured data of the 137Cs concentrations at 101 suspended particulate matter (SPM) monitoring sites, a new multi-model ensemble (MME) method of simulating 137Cs concentrations using two Atmospheric Transport and Deposition Models (ATDMs), the 131I/137Cs ratio obtained from measurement data analysis, and the internal exposure model. Based on the measurements, the maximum potential thyroid doses were estimated at 3.1-160 mSv at 5 sites in the Fukushima-Hamadori area for 1-year-old children assumed to remain outdoors, whereas they were less than 4.3 mSv at the other sites in the base case of the 131I/137Cs ratio. The spatial distribution of the maximum potential of early inhalation doses was estimated by using the MME and measurements. The inhalation thyroid doses in the evacuation scenarios were compared to the estimates reported by previous studies. The results of the present study were almost congruent with the outcomes of previous investigations except for thyroid doses contributed by highly contaminated plumes on March 12 and 15. The sensitivity analysis for the 131I/137Cs ratio indicated that these plumes carried the potential to significantly increase the thyroid doses of residents.
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Affiliation(s)
- Mai Takagi
- Fukushima Branch, National Institute for Environmental Studies, 10-2 Fukasaku Miharu Town, Fukushima, 963-7700, Japan; National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan.
| | - Toshimasa Ohara
- Fukushima Branch, National Institute for Environmental Studies, 10-2 Fukasaku Miharu Town, Fukushima, 963-7700, Japan; National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan
| | - Daisuke Goto
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan
| | - Yu Morino
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan
| | - Junya Uchida
- Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, 277-8568, Japan
| | | | - Shoji F Nakayama
- National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, 305-8506, Japan
| | - Mitsuru Ebihara
- Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo, 192-0397, Japan; Department of Earth Sciences, Waseda University, 1-6-1 Nishi-Waseda, Shinjuku-ku, Tokyo, 192-8050, Japan
| | - Yasuji Oura
- Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo, 192-0397, Japan
| | - Teruyuki Nakajima
- Earth Observation Research Center, Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki, 305-8505, Japan
| | - Haruo Tsuruta
- Remote Sensing Technology Center of Japan, 3-17-1 Toranomon, Minato-ku, Tokyo, 105-0001, Japan
| | - Yuichi Moriguchi
- Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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Relationship between environmental radiation and radioactivity and childhood thyroid cancer found in Fukushima health management survey. Sci Rep 2020; 10:4074. [PMID: 32139763 PMCID: PMC7058088 DOI: 10.1038/s41598-020-60999-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 02/18/2020] [Indexed: 11/30/2022] Open
Abstract
Environmental radioactive contamination caused by the Fukushima Dai-ichi Nuclear Power Plant accident has aroused great concern regarding a possible increase in the incidence of childhood thyroid cancer. The ultrasound examinations were conducted immediately after the accident as part of the Fukushima Health Management Survey (FHMS), which is divided into the preliminary baseline survey (PBLS) and the full-scale survey (FSS). Some of their outcomes are reported regularly and made available to the public. We have detailed measurements of the air-dose rates and radioactive elements in soil in many places all over the Fukushima prefecture. To study the dose-response relationship, we begin with the assumption that the external and internal doses are correlated with the air-dose rate and the amount of 131I in soil, respectively. We then investigate the relationship between these estimated doses and the PBLS and FSS thyroid cancer cases. Our analysis shows that the dose-response curve with the FSS data clearly differs from that with the PBLS data. Finally, we consider the potential mitigating effects of evacuation from highly contaminated areas in both external and internal exposure scenarios.
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