Radiation exposure and circulatory disease risk: Hiroshima and Nagasaki atomic bomb survivor data, 1950-2003BMJ 2010; 340 doi: https://doi.org/10.1136/bmj.b5349 (Published 15 January 2010) Cite this as: BMJ 2010;340:b5349
- Yukiko Shimizu, visiting research associate1,
- Kazunori Kodama, chief scientist2,
- Nobuo Nishi, assistant department chief 1,
- Fumiyoshi Kasagi, assistant department chief1,
- Akihiko Suyama, department chief3,
- Midori Soda, assistant department chief3,
- Eric J Grant, associate senior scientist1,
- Hiromi Sugiyama, research scientist1,
- Ritsu Sakata, research scientist1,
- Hiroko Moriwaki, research assistant1,
- Mikiko Hayashi, research assistant1,
- Manami Konda, research assistant1,
- Roy E Shore, vice chairman and chief of research2
- 1Department of Epidemiology, Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan
- 2Radiation Effects Research Foundation, Hiroshima
- 3Department of Epidemiology, Radiation Effects Research Foundation, Nagasaki 850-0013, Japan
- Correspondence to: Y Shimizu
- Accepted 8 September 2009
Objective To investigate the degree to which ionising radiation confers risk of mortality from heart disease and stroke.
Design Prospective cohort study with more than 50 years of follow-up.
Setting Atomic bomb survivors in Hiroshima and Nagasaki, Japan.
Participants 86 611 Life Span Study cohort members with individually estimated radiation doses from 0 to >3 Gy (86% received <0.2 Gy).
Main outcome measures Mortality from stroke or heart disease as the underlying cause of death and dose-response relations with atomic bomb radiation.
Results About 9600 participants died of stroke and 8400 died of heart disease between 1950 and 2003. For stroke, the estimated excess relative risk per gray was 9% (95% confidence interval 1% to 17%, P=0.02) on the basis of a linear dose-response model, but an indication of possible upward curvature suggested relatively little risk at low doses. For heart disease, the estimated excess relative risk per gray was 14% (6% to 23%, P<0.001); a linear model provided the best fit, suggesting excess risk even at lower doses. However, the dose-response effect over the restricted dose range of 0 to 0.5 Gy was not significant. Prospective data on smoking, alcohol intake, education, occupation, obesity, and diabetes had almost no impact on the radiation risk estimates for either stroke or heart disease, and misdiagnosis of cancers as circulatory diseases could not account for the associations seen.
Conclusion Doses above 0.5 Gy are associated with an elevated risk of both stroke and heart disease, but the degree of risk at lower doses is unclear. Stroke and heart disease together account for about one third as many radiation associated excess deaths as do cancers among atomic bomb survivors.
We thank the members of Radiation Effects Research Foundation Master File section for their diligent efforts to provide accurate data on mortality in the Life Span Study and Hiroshima and Nagasaki tumour and tissue registries for their approval for the use of the data. We also thank Yoshisuke Nonaka for statistical advice.
Contributors: YS, RES, KK, NN, FK, EJG, HS, RS, AS, and MS contributed to the study concept and design and to writing the paper. NN, HS, and MS advised on the tumour registry data. HM, MH, and MK contributed to data preparation for statistical analyses. All authors participated in interpreting the results. YS is the guarantor.
Funding: The Radiation Effects Research Foundation (RERF), Hiroshima and Nagasaki, Japan is a private, non-profit foundation funded by the Japanese Ministry of Health, Labour and Welfare (MHLW) and the US Department of Energy (DOE), the latter in part through the National Academy of Sciences. This publication was supported by RERF research protocol 1-75. The views expressed in this paper are those of the authors alone.
Competing interests: None declared.
Ethical approval: The research was conducted under the formal approval of RERF’s Human Investigation Committee.
Data sharing: Detailed tabulation of data used for the analysis and the statistical code are available from the corresponding author.
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