scholarly journals Neutron relative biological effectiveness in Hiroshima and Nagasaki atomic bomb survivors: a critical review

2016 ◽  
Vol 57 (6) ◽  
pp. 583-595 ◽  
Author(s):  
Masao S. Sasaki ◽  
Satoru Endo ◽  
Masaharu Hoshi ◽  
Taisei Nomura
Keyword(s):  
Cancer Risk ◽  
Radiation Exposure ◽  
Atomic Bomb ◽  
Relative Biological Effectiveness ◽  
Weighting Factor ◽  
Atomic Bomb Survivors ◽  
Biological Effectiveness ◽  
Γ Rays ◽  
Neutron Component ◽  
Risk Of Cancer

Abstract The calculated risk of cancer in humans due to radiation exposure is based primarily on long-term follow-up studies, e.g. the life-span study (LSS) on atomic bomb (A-bomb) survivors in Hiroshima and Nagasaki. Since A-bomb radiation consists of a mixture of γ-rays and neutrons, it is essential that the relative biological effectiveness (RBE) of neutrons is adequately evaluated if a study is to serve as a reference for cancer risk. However, the relatively small neutron component hampered the direct estimation of RBE in LSS data. To circumvent this problem, several strategies have been attempted, including dose-independent constant RBE, dose-dependent variable RBE, and dependence on the degrees of dominance of intermingled γ-rays. By surveying the available literature, we tested the chromosomal RBE of neutrons as the biological endpoint for its equivalence to the microdosimetric quantities obtained using a tissue-equivalent proportional counter (TEPC) in various neutron fields. The radiation weighting factor, or quality factor, Qn, of neutrons as expressed in terms of the energy dependence of the maximum RBE, RBEm, was consistent with that predicted by the TEPC data, indicating that the chromosomally measured RBE was independent of the magnitude of coexisting γ-rays. The obtained neutron RBE, which varied with neutron dose, was confirmed to be the most adequate RBE system in terms of agreement with the cancer incidence in A-bomb survivors, using chromosome aberrations as surrogate markers. With this RBE system, the cancer risk in A-bomb survivors as expressed in unit dose of reference radiation is equally compatible with Hiroshima and Nagasaki cities, and may be potentially applicable in other cases of human radiation exposure.

scholarly journals Cancer mortality in residents of the terrain-shielded area exposed to fallout from the Nagasaki atomic bombing

2017 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Kenichi Yokota ◽  
Mariko Mine ◽  
Hisayoshi Kondo ◽  
Naoki Matsuda ◽  
Yoshisada Shibata ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Cancer Mortality ◽  
Atomic Bomb ◽  
Control Group ◽  
Low Dose Radiation ◽  
Atomic Bomb Survivors ◽  
Direct Exposure ◽  
Effects Of Radiation ◽  
Risk Of Cancer

Abstract The health effects of radiation exposure from the atomic bomb fallout remain unclear. The objective of the present study is to elucidate the association between low-dose radiation exposure from the atomic bomb fallout and cancer mortality among Nagasaki atomic bomb survivors. Of 77 884 members in the Nagasaki University Atomic Bomb Survivors Cohort, 610 residents in the terrain-shielded area with fallout were selected for this analysis; 1443 residents in the terrain-shielded area without fallout were selected as a control group; and 3194 residents in the direct exposure area were also selected for study. Fifty-two deaths due to cancer in the terrain-shielded fallout area were observed during the follow-up period from 1 January 1970 to 31 December 2012. The hazard ratio for cancer mortality in the terrain-shielded fallout area was 0.90 (95% confidence interval: 0.65–1.24). No increase in the risk of cancer mortality was observed, probably because the dose of the radiation exposure was low for residents in the terrain-shielded fallout areas of the Nagasaki atomic bomb, and also because the number of study subjects was small.

scholarly journals Risk of cancer associated with low-dose radiation exposure: comparison of results between the INWORKS nuclear workers study and the A-bomb survivors study

2021 ◽  
Vol 60 (1) ◽  
pp. 23-39
Author(s):  
Klervi Leuraud ◽  
David B. Richardson ◽  
Elisabeth Cardis ◽  
Robert D. Daniels ◽  
Michael Gillies ◽  
...  
Keyword(s):  
Low Dose ◽  
Atomic Bomb ◽  
Absolute Risk ◽  
Joint Analysis ◽  
Solid Cancer ◽  
Atomic Bomb Survivors ◽  
Nuclear Workers ◽  
Long Term Follow Up ◽  
Primary Basis ◽  
Risk Of Cancer

AbstractThe Life Span Study (LSS) of Japanese atomic bomb survivors has served as the primary basis for estimates of radiation-related disease risks that inform radiation protection standards. The long-term follow-up of radiation-monitored nuclear workers provides estimates of radiation-cancer associations that complement findings from the LSS. Here, a comparison of radiation-cancer mortality risk estimates derived from the LSS and INWORKS, a large international nuclear worker study, is presented. Restrictions were made, so that the two study populations were similar with respect to ages and periods of exposure, leading to selection of 45,625 A-bomb survivors and 259,350 nuclear workers. For solid cancer, excess relative rates (ERR) per gray (Gy) were 0.28 (90% CI 0.18; 0.38) in the LSS, and 0.29 (90% CI 0.07; 0.53) in INWORKS. A joint analysis of the data allowed for a formal assessment of heterogeneity of the ERR per Gy across the two studies (P = 0.909), with minimal evidence of curvature or of a modifying effect of attained age, age at exposure, or sex in either study. There was evidence in both cohorts of modification of the excess absolute risk (EAR) of solid cancer by attained age, with a trend of increasing EAR per Gy with attained age. For leukemia, under a simple linear model, the ERR per Gy was 2.75 (90% CI 1.73; 4.21) in the LSS and 3.15 (90% CI 1.12; 5.72) in INWORKS, with evidence of curvature in the association across the range of dose observed in the LSS but not in INWORKS; the EAR per Gy was 3.54 (90% CI 2.30; 5.05) in the LSS and 2.03 (90% CI 0.36; 4.07) in INWORKS. These findings from different study populations may help understanding of radiation risks, with INWORKS contributing information derived from cohorts of workers with protracted low dose-rate exposures.

scholarly journals Radiation effects on atherosclerosis in atomic bomb survivors: a cross‐sectional study using structural equation modeling

2021 ◽  
Vol 36 (4) ◽  
pp. 401-414
Author(s):  
Tomoki Nakamizo ◽  
John Cologne ◽  
Kismet Cordova ◽  
Michiko Yamada ◽  
Tetsuya Takahashi ◽  
...  
Keyword(s):  
Arterial Stiffness ◽  
Radiation Exposure ◽  
Structural Equation ◽  
Atomic Bomb ◽  
Cross Sectional Study ◽  
Equation Modeling ◽  
Study Cohort ◽  
Sectional Study ◽  
Cross Sectional ◽  
Atomic Bomb Survivors

AbstractPast reports indicated that total-body irradiation at low to moderate doses could be responsible for cardiovascular disease risks, but the mechanism remains unclear. The purpose of this study was to investigate the association between radiation exposure and atherosclerosis, an underlying pathology of cardiovascular diseases, in the Japanese atomic bomb survivors. We performed a cross-sectional study measuring 14 clinical-physiological atherosclerosis indicators during clinical exams from 2010 to 2014 in 3274 participants of the Adult Health Study cohort. Multivariable analyses were performed by using a structural equation model with latent factors representing underlying atherosclerotic pathologies: (1) arterial stiffness, (2) calcification, and (3) plaque　as measured with indicators chosen a priori on the basis of clinical-physiological knowledge. Radiation was linearly associated with calcification (standardized coefficient per Gy 0.15, 95 % confidence interval: CI [0.070, 0.23]) and plaque (0.11, 95 % CI [0.029, 0.20]), small associations that were comparable to about 2 years of aging per Gy of radiation exposure, but not with arterial stiffness (0.036, 95 % CI [− 0.025, 0.095]). The model fitted better and had narrower confidence intervals than separate ordinary regression models explaining individual indicators independently. The associations were less evident when the dose range was restricted to a maximum of 2 or 1 Gy. By combining individual clinical-physiological indicators that are correlated because of common, underlying atherosclerotic pathologies, we found a small, but significant association of radiation with atherosclerosis.

scholarly journals Radiation Risks of Uterine Cancer in Atomic Bomb Survivors: 1958–2009

2018 ◽  
Vol 2 (4) ◽  
Author(s):  
Mai Utada ◽  
Alina V Brenner ◽  
Dale L Preston ◽  
John B Cologne ◽  
Ritsu Sakata ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Radiation Exposure ◽  
Radiation Effect ◽  
Atomic Bomb ◽  
Uterine Cancer ◽  
Radiation Risk ◽  
Atomic Bomb Survivors ◽  
Exposure Age ◽  
Modifying Effect ◽  
Effect Of Age

Abstract Background Ionizing radiation is known to be capable of causing cancer of many organs, but its relationship with uterine cancer has not been well characterized. Methods We studied incidence of uterine cancer during 1958–2009 among 62 534 female atomic bomb survivors. Using Poisson regression analysis, we fitted excess relative risk (ERR) models to uterine cancer rates adjusted for several lifestyle and reproductive factors. Person-years at risk were also adjusted for the probability of prior hysterectomy, because it could affect the subsequent risk of uterine cancer. We assessed the modifying effect of age and other factors on the radiation risk. For analysis of the modifying effect of age at radiation exposure around menarche, we compared the radiation risk for several exposure-age categories as well as using parametric models. Results There were 224 uterine corpus cancers and 982 cervical cancers. We found a significant association between radiation dose and risk of corpus cancer (ERR per Gray [ERR/Gy] = 0.73, 95% confidence interval [CI] = 0.03 to 1.87) but not for cervical cancer (ERR/Gy = 0.00, 95% CI = −0.22 to 0.31). For corpus cancer, we found statistically significant heterogeneity in ERR/Gy by age (Pheterogeneity = .001) with elevated risk for women exposed to radiation between ages 11 and 15 years (ERR/Gy = 4.10, 95% CI = 1.47 to 8.42) and no indication of a radiation effect for exposures before or after this exposure-age range. Conclusions The current data suggest that uterine corpus is especially sensitive to the carcinogenic effect of radiation exposure occurring during the mid-pubertal period preceding menarche. There is little evidence for a radiation effect on cervical cancer risk.

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