Effect of Recent Changes in Atomic Bomb Survivor Dosimetry on Cancer Mortality Risk Estimates
- 1 October 2004
- journal article
- Published by Radiation Research Society in Radiation Research
- Vol. 162 (4), 377-389
- https://doi.org/10.1667/rr3232
Abstract
Preston, D. L., Pierce, D. A., Shimizu, Y., Cullings, H. M., Fujita, S., Funamoto, S. and Kodama, K. Effect of Recent Changes in Atomic Bomb Survivor Dosimetry on Cancer Mortality Risk Estimates. Radiat. Res. 162, 377–389 (2004). The Radiation Effects Research Foundation has recently implemented a new dosimetry system, DS02, to replace the previous system, DS86. This paper assesses the effect of the change on risk estimates for radiation-related solid cancer and leukemia mortality. The changes in dose estimates were smaller than many had anticipated, with the primary systematic change being an increase of about 10% in γ-ray estimates for both cities. In particular, an anticipated large increase of the neutron component in Hiroshima for low-dose survivors did not materialize. However, DS02 improves on DS86 in many details, including the specifics of the radiation released by the bombs and the effects of shielding by structures and terrain. The data used here extend the last reported follow-up for solid cancers by 3 years, with a total of 10,085 deaths, and extends the follow-up for leukemia by 10 years, with a total of 296 deaths. For both solid cancer and leukemia, estimated age–time patterns and sex difference are virtually unchanged by the dosimetry revision. The estimates of solid-cancer radiation risk per sievert and the curvilinear dose response for leukemia are both decreased by about 8% by the dosimetry revision, due to the increase in the γ-ray dose estimates. The apparent shape of the dose response is virtually unchanged by the dosimetry revision, but for solid cancers, the additional 3 years of follow-up has some effect. In particular, there is for the first time a statistically significant upward curvature for solid cancer on the restricted dose range 0–2 Sv. However, the low-dose slope of a linear-quadratic fit to that dose range should probably not be relied on for risk estimation, since that is substantially smaller than the linear slopes on ranges 0–1 Sv, 0–0.5 Sv, and 0– 0.25 Sv. Although it was anticipated that the new dosimetry system might reduce some apparent dose overestimates for Nagasaki factory workers, this did not materialize, and factory workers have significantly lower risk estimates. Whether or not one makes allowance for this, there is no statistically significant city difference in the estimated cancer risk.Keywords
This publication has 13 references indexed in Scilit:
- Studies of Mortality of Atomic Bomb Survivors. Report 13: Solid Cancer and Noncancer Disease Mortality: 1950–1997Radiation Research, 2003
- The impact of possible modifications to the DS86 dosimetry on neutron risk and relative biological effectivenessJournal of Radiological Protection, 2002
- Stable Chromosome Aberrations in Atomic Bomb Survivors: Results from 25 Years of InvestigationRadiation Research, 2001
- Radiation-Related Cancer Risks at Low Doses among Atomic Bomb SurvivorsRadiation Research, 2000
- The effects of neutrons in Hiroshima. Implications for the risk estimatesComptes Rendus de l'Académie des Sciences - Series III - Sciences de la Vie, 1999
- Residual 60Co Activity in Steel Samples Exposed to the Hiroshima Atomic-Bomb NeutronsHealth Physics, 1998
- Neutron versus Á-ray risk estimatesRadiation and Environmental Biophysics, 1997
- 137Cs Concentration in Soil Samples from an Early Survey of Hiroshima Atomic Bomb and Cumulative Dose Estimation from the FalloutHealth Physics, 1996
- Residual 152Eu and 60Co Activities Induced by Neutrons from the Hiroshima Atomic BombHealth Physics, 1993
- Neutron Discrepancies in the DS86 Hiroshima Dosimetry SystemHealth Physics, 1992