@article{oai:repo.qst.go.jp:00046502,
 author = {Iwaoka, Kazuki and Tabe, Hiroyuki and Yonehara, Hidenori and 岩岡 和輝 and 田部 裕章 and 米原 英典},
 issue = {2},
 journal = {Journal of Radioanalytical and Nuclear Chemistry},
 month = {Feb},
 note = {In Japan, bedrock bath instruments and hot spring instruments that contain natural radioactive nuclides are commercially available. In this study, such instruments containing natural radioactive nuclides, currently distributed in Japan, were collected and the radioactivity concentration of 238U series, 232Th series, and 40K in them was determined by gamma ray spectrum analyses. Effective doses to workers and general consumers handling the materials were estimated, revealing the radioactivity concentration of 238U series, 232Th series, and 40K to be lower than critical values given in the IAEA Safety Guide. The maximum effective doses to workers and general consumers were 210 and 6.1 uSv y-1, respectively. These values are lower than the intervention exemption level (1000 uSv y-1) given in ICRP Publ. 82.},
 pages = {817--821},
 title = {Natural radioactivity of bedrock bath instruments and hot spring instruments in Japan},
 volume = {295},
 year = {2013}
}