title: Evaluation of environmental contamination and estimated exposure doses after residents return home in Kawauchi Village, Fukushima Prefecture.
abstract: The external and internal exposure doses due to artificial radionuclides after the return of residents to their homes in Kawauchi Village, Fukushima Prefecture, including the restricted area within a 20-km radius from the Fukushima Dai-ichi Nuclear Power Plant (FNPP), were evaluated by gamma spectrometry of the soils and local agricultural products. The prevalent dose-forming artificial radionuclides from all samples were determined to be (134)Cs and (137)Cs (radiocesium). The estimated external effective doses from soils sampled on December 24 and 25, 2012 were 0.0017-9.2 mSv/y in the areas within a 20- to 30-km radius from the FNPP and 0.39-1.3 mSv/y in the areas within a 20-km radius from the FNPP. These levels appeared to be decreasing, despite the distance from the FNPP (median: 0.21 (0.012-0.56) mSv/y), compared to the levels just before the return of the residents to their homes on December 19 and 20, 2011 (median: 0.85 (0.40-1.4) mSv/y). The committed effective doses from the local agricultural samples in Kawauchi Village from May 1, 2012 to March 31, 2013 were sufficiently low, in the range of 18-44 μSv/y for males and 20-48 μSv/y for females (the range was 18-48 μSv/y for children and 25-43 μSv/y for adults), compared to the public dose limit (1 mSv/y, ICRP, 1991), although the potential for radiation exposure still exists. Residents who have not yet returned may be able to return to their homes with a long-term follow-up of environmental monitoring and countermeasures to reduce unnecessary radiation exposure.
authors.affiliation: Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University , Nagasaki, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Taira
authors.forename: Naomi
authors.initials: N
authors.lastname: Hayashida
authors.forename: Makiko
authors.initials: M
authors.lastname: Orita
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Juichi
authors.initials: J
authors.lastname: Ide
authors.forename: Yuukou
authors.initials: Y
authors.lastname: Endo
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yamashita
authors.forename: Noboru
authors.initials: N
authors.lastname: Takamura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005504:Food Analysis; D062406:Fukushima Nuclear Accident; D005843:Geography; D006801:Humans; D007231:Infant, Newborn; D007564:Japan; D008297:Male; D008875:Middle Aged; D011834:Radiation Monitoring / Q000379:methods*; D011868:Radioisotopes / Q000032:analysis; D012990:Soil Pollutants, Radioactive / Q000032:analysis; D013051:Spectrometry, Gamma; D055815:Young Adult
chemical_list: D011868:Radioisotopes; D012990:Soil Pollutants, Radioactive