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ID 40782
file
creator
Hara, Noriyuki
Ohtaki, Megu
subject
Atomic-bomb survivors
Dose-response relationship
Exposure distance
Heart disease mortality
NDC
Medical sciences
abstract
Heart disease (HD) mortality is the second leading cause of death in Japan. The HD mortality risk among Atomic bomb survivors is slightly positive but shows a statistically significant dose-response relationship with initial radiation dose, as reported by the Radiation Effects Research Foundation. In that report, dosimetry was based on initial radiation only, with the effect of indirect radiation dose not taken into consideration. The atomic bomb radiation, however, consisted of both initial and residual radiation. We reevaluated the dose-response relationship for HD mortality using exposure distance (ground distance between the location where exposed and the hypocenter) as a surrogate indicator of radiation dose. At Hiroshima University, a cohort study has been conducted with Hiroshima Atomic Bomb Survivors (ABS) since 1970. We selected 29605 subjects from the ABS who were exposed at 3.5 km or less from the hypocenter and alive on January 1, 1970. These subjects, referred to as “Hiroshima hibakusha” in this paper, were followed until December 31, 2010. We stratified the cohort data with respect to sex and age at the time of bombing (ATB) into 10-year age groups. For each stratum, by applying an extended Cox regression model with time-dependent covariates, we analyzed the risk of HD mortality using either initial radiation dose or exposure distance as an explanatory variable. The results indicate a high excess risk in males and older age ATB females who were exposed near the hypocenter. This difference may be explained by the effect of female sex hormone on the circulatory system among young age ATB females. Some unknown risk factor related to exposure distance was also implicated in the elevated risk of HD among the Hiroshima hibakusha, especially in males. This necessitates further study.
description
This research was supported in part by Grants-in-Aid for Scientific Research (A) 24249039 (2012–2014), and the Joint Usage/Research Center (RIRBM), Hiroshima University.
journal title
Hiroshima Journal of Medical Sciences
volume
Volume 65
issue
Issue 2
start page
45
end page
51
date of issued
2016-06
publisher
Hiroshima University Medical Press
issn
0018-2052
ncid
language
eng
nii type
Departmental Bulletin Paper
HU type
Departmental Bulletin Papers
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 2016 Hiroshima University Medical Press
department
Graduate School of Biomedical & Health Sciences
Research Institute for Radiation Biology and Medicine
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