@article{oai:repo.qst.go.jp:00047302,
 author = {Kubota, Yoshihisa and Takahashi, Hiroyuki and Watanabe, Yoshito and Fuma, Shoichi and Kawaguchi, Isao and Aoki, Masanari and Kubota, Masahide and Furuhata, Yoshiaki and Shigemura, Yusaku and Yamada, Fumio and Ishikawa, Takahiro and Obara, Satoshi and Yoshida, Satoshi and 久保田 善久 and 高橋 博路 and 渡辺 嘉人 and 府馬 正一 and 川口 勇生 and 石川 剛弘 and 小原 哲 and 吉田 聡},
 journal = {Journal of Environmental Radioactivity},
 month = {Jan},
 note = {The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium (134Cs and 137Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50–fold difference between minimum and maximum whole-body activityconcentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 µGy h-1 (1.2 mGy d-1), even 3 years after the accident. This dose rate exceeds 0.1–1 mGy d-1 derived consideration reference level for Reference rat proposed by the International Commission on Radiological Protection (ICRP).},
 pages = {124--131},
 title = {Estimation of absorbed radiation dose rates in wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi nuclear power plant accident},
 volume = {142},
 year = {2015}
}