Original Paper

Radiation and Environmental Biophysics

, Volume 51, Issue 2, pp 133-141

Open Access This content is freely available online to anyone, anywhere at any time.

Investigation on circular asymmetry of geographical distribution in cancer mortality of Hiroshima atomic bomb survivors based on risk maps: analysis of spatial survival data

  • Tetsuji TondaAffiliated withDepartment of Environmetrics and Biometrics, Research Institute for Radiation Biology and Medicine, Hiroshima University Email author 
  • , Kenichi SatohAffiliated withDepartment of Environmetrics and Biometrics, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Keiko OtaniAffiliated withDepartment of Environmetrics and Biometrics, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Yuya SatoAffiliated withDivision of Radiation Information Registry, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Hirofumi MaruyamaAffiliated withDepartment of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Hideshi KawakamiAffiliated withDepartment of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Satoshi TashiroAffiliated withDivision of Radiation Information Registry, Research Institute for Radiation Biology and Medicine, Hiroshima UniversityDepartment of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Masaharu HoshiAffiliated withDepartment of Radiation Biophysics, Research Institute for Radiation Biology and Medicine, Hiroshima University
  • , Megu OhtakiAffiliated withDepartment of Environmetrics and Biometrics, Research Institute for Radiation Biology and Medicine, Hiroshima University

Abstract

While there is a considerable number of studies on the relationship between the risk of disease or death and direct exposure from the atomic bomb in Hiroshima, the risk for indirect exposure caused by residual radioactivity has not yet been fully evaluated. One of the reasons is that risk assessments have utilized estimated radiation doses, but that it is difficult to estimate indirect exposure. To evaluate risks for other causes, including indirect radiation exposure, as well as direct exposure, a statistical method is described here that evaluates risk with respect to individual location at the time of atomic bomb exposure instead of radiation dose. In addition, it is also considered to split the risks into separate risks due to direct exposure and other causes using radiation dose. The proposed method is applied to a cohort study of Hiroshima atomic bomb survivors. The resultant contour map suggests that the region west to the hypocenter has a higher risk compared to other areas. This in turn suggests that there exists an impact on risk that cannot be explained by direct exposure.

Keywords

Atomic bomb survivors Direct exposure Indirect exposure Spatial survival data Spatially varying coefficient