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. 2022;32(Suppl_XII):S11-S22.
doi: 10.2188/jea.JE20210166.

External Doses Available for Epidemiological Studies Related to the Fukushima Health Management Survey: First 4-month Individual Doses and Municipality-average Doses for the First Year

Tetsuo Ishikawa  1 , Seiji Yasumura  1 , Keiichi Akahane  2 , Shunsuke Yonai  2 , Akira Sakai  1 , Osamu Kurihara  2 , Mitsuaki Hosoya  1 , Ritsu Sakata  3 , Tetsuya Ohira  1 , Hitoshi Ohto  1 , Kenji Kamiya  1   4
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External Doses Available for Epidemiological Studies Related to the Fukushima Health Management Survey: First 4-month Individual Doses and Municipality-average Doses for the First Year

Tetsuo Ishikawa et al. J Epidemiol. 2022.

Abstract

Background: One of the components of the Fukushima Health Management Survey (FHMS) is the Basic Survey, which estimates individual external doses for the first 4 months after the 2011 nuclear power plant accident. However, external exposure continues long-term. According to estimations by international organizations, the external dose during the first year accounts for a significant part of the long-term dose. Thus, the present study was intended to estimate the first-year doses by extrapolating the Basic Survey results.

Methods: For most municipalities of non-evacuated areas, ambient dose rate had been continuously measured for at least one designated point in each municipality after the accident. In the present study, a municipality-average dose received by residents for a period was assumed to be proportional to the ambient dose measured at the designated point of that municipality during the same period. Based on this assumption, 4-month municipality-average doses calculated from the Basic Survey results were extrapolated to obtain first-year doses.

Results: The extrapolated first-year doses for 49 municipalities in the non-evacuated areas had a good correlation with those estimated by UNSCEAR, although the extrapolated doses were generally higher (slope of the regression line: 1.23). The extrapolated municipality-average doses were in reasonable agreement (within 30%) with personal dosimeter measurements, suggesting that the extrapolation was reasonable.

Conclusion: The present paper reports the first 4-month average doses for all 59 municipalities of Fukushima Prefecture and the extrapolated first-year doses for 49 municipalities. The extrapolated doses will be the basis for future epidemiological studies related to the FHMS.

Keywords: Fukushima accident; external dose; first year.

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Conflict of interest statement

Conflicts of interest: None declared.

Figures

Figure 1.
Figure 1.. Technical terms related to dose used in the present paper
Figure 2.
Figure 2.. Background radiation sources and difference in sensitivity to these sources by measurement devices
Figure 3.
Figure 3.. Scheme of the method for estimating first-year dose and its validation
Figure 4.
Figure 4.. Locations of MPs in seven regions of Fukushima Prefecture. As shown in Figure 1, two types of MPs were used. MPs for Aizuwakamatsu and Minamiaizu were the stationary-type MP (S-MP) which measured absorbed dose in air, while the other MPs were the portable-type MP (P-MP) which measured ambient dose equivalent.
Figure 5.
Figure 5.. Changes in ambient equivalent dose rate in an early stage after the accident. Data reported from the five S-MPs were plotted.
Figure 6.
Figure 6.. Changes in ambient dose equivalent measured with SVs in the first year. (A) Soma City Office in Soso region and (B) Kunimi Town Office in Kempoku region. Background dose was subtracted. Di∗(4m) and Di∗(8m) were estimated based on yellow shaded areas. Figure 7 shows locations of the municipalities.
Figure 7.
Figure 7.. Ambient dose equivalent rate map of Fukushima Prefecture and the first 4-month average individual doses (bar graphs) classified by residential places at the time of accident. Decay correction for ambient dose equivalent rate was made to May 31, 2012. Ambient dose equivalent rate data were taken from: https://emdb.jaea.go.jp/emdb/
Figure 8.
Figure 8.. Comparison of first-year doses estimated by UNSCEAR and extrapolated doses by the present study
See this image and copyright information in PMC

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References

    1. United Nations Scientific Committee on the Effects of Atomic Radiation. UNSCEAR 2013 Report Annex A: Levels and effects of radiation exposure due to the nuclear accident after the 2011 Great East-Japan Earthquake and Tsunami. New York: United Nations; 2014.
    1. Murase K, Murase J, Machidori K, Mizuno K, Hayashi Y, Kohri K. Nationwide increase in cryptorchidism after the Fukushima Nuclear Accident. Urology. 2018;118:65–70. 10.1016/j.urology.2018.04.033 - DOI - PubMed
    1. Kojima Y, Yokoya S, Kurita N, et al. . Cryptorchidism after the Fukushima Daiichi Nuclear Power Plant accident: causation or coincidence? Fukushima J Med Sci. 2019;65(3):76–98. 10.5387/fms.2019-22 - DOI - PMC - PubMed
    1. Yamamoto H, Hayashi K, Scherb H. Association between the detection rate of thyroid cancer and the external radiation dose-rate after the nuclear power plant accidents in Fukushima, Japan. Medicine. 2019;98(37):e17165. 10.1097/MD.0000000000017165 - DOI - PMC - PubMed
    1. Ohira T, Shimura H, Hayashi F, et al. . Absorbed radiation doses in the thyroid as estimated by UNSCEAR and subsequent risk of childhood thyroid cancer following the Great East Japan Earthquake. J Radiat Res. 2020;61(2):243–248. 10.1093/jrr/rrz104 - DOI - PMC - PubMed

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