Mortality among U.S. military participants at eight aboveground nuclear weapons test series

Moon, Mars and Minds: Evaluating Parkinson's disease mortality among U.S. radiation workers and veterans in the million person study of low-dose effects

BACKGROUND

Radiation is one of the most important stressors related to missions in space beyond Earth's orbit. Epidemiologic studies of exposed workers have reported elevated rates of Parkinson's disease. The importance of cognitive dysfunction related to low-dose rate radiation in humans is not defined. A meta-analysis was conducted of six cohorts in the Million Person Study (MPS) of low-dose health effects to learn whether there is consistent evidence that Parkinson's disease is associated with radiation dose to brain.

MATERIALS AND METHODS

The MPS evaluates all causes of death among U.S. radiation workers and veterans, including Parkinson's disease. Systematic and consistent methods are applied to study all categories of workers including medical radiation workers, industrial radiographers, nuclear power plant workers, atomic veterans, and Manhattan Projects workers at the Los Alamos National Laboratory and at Rocky Flats. Consistent methods for all cohorts are used to estimate organ-specific doses and to obtain vital status and cause of death.

RESULTS

The meta-analysis include 6 cohorts within the MPS, consisting of 517,608 workers and 17,219,001 person-years of observation. The mean dose to brain ranged from 6.9 to 47.6 mGy and the maximum dose from 0.76 to 2.7 Gy. Five of the 6 cohorts revealed positive associations with Parkinson's disease. The overall summary estimate from the meta-analysis was statistically significant based on 1573 deaths due to Parkinson's disease. The summary excess relative risk at 100 mGy was 0.17 (95% CI: 0.05; 0.29).

CONCLUSIONS

Parkinson's disease was positively associated with radiation in the MPS cohorts indicating the need for careful evaluation as to causality in other studies, delineation of possible mechanisms, and assessing possible implications for space travel as well as radiation protection guidance for terrestrial workers.

Asbestos-related cancer in naval personnel: findings from participants in the British nuclear tests 1952-1967

Asbestos-containing materials (ACM) were present in British and Australian naval vessels throughout the twentieth century. The aim of this study was to identify and quantify the incidence of cancer in naval personnel from onboard asbestos exposure. Subjects were four cohorts of subjects who had served in the armed forces of the United Kingdom and Australia in the 1950s and 1960s. All cohorts had previously been studied, three of them in relation to radiation exposures from British nuclear testing. Comparisons of SIRs between services were made to identify cancers attributable to asbestos exposure. Excess mesotheliomas were found in naval personnel in all cohorts. In all but one cohort the lung cancer incidence was highest in navy personnel. Comparison of other smoking-related conditions indicated that the excess in navy personnel was not smoking-related. The relatively high SIRs for mesothelioma and the occurrence of deaths from asbestosis were indicative of high levels of asbestos exposure, with an expectation of cases of asbestos-related lung cancer. The findings are consistent with the occurrence of significant excesses of mesotheliomas. In addition, notwithstanding some inconsistencies in the results between the cohorts, we estimated that approximately 27% of lung cancers in Australian seamen and 12% in British seamen were related to onboard asbestos exposure.

An updated evaluation of reported no-observed adverse effect levels for chrysotile, amosite, and crocidolite asbestos for lung cancer and mesothelioma

This analysis updates two previous analyses that evaluated the exposure-response relationships for lung cancer and mesothelioma in chrysotile-exposed cohorts. We reviewed recently published studies, as well as updated information from previous studies. Based on the 16 studies considered for chrysotile (<10% amphibole), we identified the "no-observed adverse effect level" (NOAEL) for lung cancer and/or mesothelioma; it should be noted that smoking or previous or concurrent occupational exposure to amphiboles (if it existed) was not controlled for. NOAEL values ranged from 2.3-<11.5 f/cc-years to 1600-3200 f/cc-years for lung cancer and from 100-<400 f/cc-years to 800-1599 f/cc-years for mesothelioma. The range of best-estimate NOAELs was estimated to be 97-175 f/cc-years for lung cancer and 250-379 f/cc-years for mesothelioma. None of the six cohorts of cement or friction product manufacturing workers exhibited an increased risk at any exposure level, while all but one of the six studies of textile workers reported an increased risk at one or more exposure levels. This is likely because friction and cement workers were exposed to much shorter chrysotile fibers. Only eight cases of peritoneal mesothelioma were reported in all studies on predominantly chrysotile-exposed cohorts combined. This analysis also proposed best-estimate amosite and crocidolite NOAELs for mesothelioma derived by the application of relative potency estimates to the best-estimate chrysotile NOAELs for mesothelioma and validated by epidemiology studies with exposure-response information. The best-estimate amosite and crocidolite NOAELs for mesothelioma were 2-5 f/cc-years and 0.6-1 f/cc-years, respectively. The rate of peritoneal mesothelioma in amosite- and crocidolite-exposed cohorts was between approximately 70- to 100-fold and several-hundred-fold higher than in chrysotile-exposed cohorts, respectively. These findings will help characterize potential worker and consumer health risks associated with historical and current chrysotile, amosite, and crocidolite exposures.

Exposure to Ionizing Radiation and Risk of Dementia: A Systematic Review and Meta-Analysis

The number of people living with dementia is rising globally as life expectancy increases. Dementia is a multifactorial disease. Due to the ubiquity of radiation exposure in medical and occupational settings, the potential association between radiation and dementia, and its subtypes (Alzheimer's and Parkinson's disease), is of particular importance. There has also been an increased interest in studying radiation induced dementia risks in connection with the long-term manned space travel proposed by The National Aeronautics and Space Administration (NASA). Our aim was to systematically review the literature on this topic, and use meta-analysis to generate a summary measure of association, assess publication bias and explore sources of heterogeneity across studies. We identified five types of exposed populations for this review: 1. survivors of atomic bombings in Japan; 2. patients treated with radiation therapy for cancer or other diseases; 3. occupationally exposed workers; 4. those exposed to environmental radiation; and 5. patients exposed to radiation from diagnostic radiation imaging procedures. We included studies that considered incident or mortality outcomes for dementia and its subtypes. Following PRISMA guidelines, we systematically searched the published literature indexed in PubMed between 2001 and 2022. We then abstracted the relevant articles, conducted a risk-of-bias assessment, and fit random effects models using the published risk estimates. After we applied our eligibility criteria, 18 studies were identified for review and retained for meta-analysis. For dementia (all subtypes), the summary relative risk was 1.11 (95% CI: 1.04, 1.18; P = 0.001) comparing individuals receiving 100 mSv of radiation to those with no exposure. The corresponding summary relative risk for Parkinson's disease incidence and mortality was 1.12 (95% CI 1.07, 1.17; P <0.001). Our results provide evidence that exposure to ionizing radiation increases the risk of dementia. However, our findings should be interpreted with caution due to the small number of included studies. Longitudinal studies with improved exposure characterization, incident outcomes, larger sample size, and the ability to adjust for effects of potential confounders are needed to better assess the possible causal link between ionizing radiation and dementia.

Mortality among medical radiation workers in the United States, 1965-2016

BACKGROUND

Estimates of radiation risks following prolonged exposures at low doses and low-dose rates are uncertain. Medical radiation workers are a major component of the Million Person Study (MPS) of low-dose health effects. Annual personal dose equivalents, H_P(10), for individual workers are available to facilitate dose-response analyses for lung cancer, leukemia, ischemic heart disease (IHD) and other causes of death.

MATERIALS AND METHODS

The Landauer, Inc. dosimetry database identified 109,019 medical and associated radiation workers first monitored 1965-1994. Vital status and cause of death were determined through 2016. Mean absorbed doses to red bone marrow (RBM), lung, heart, and other organs were estimated by adjusting the recorded H_P(10) for each worker by scaling factors, accounting for exposure geometry, the energy of the incident photon radiation, sex of the worker and whether an apron was worn. There were 4 exposure scenarios: general radiology characterized by low-energy x-ray exposure with no lead apron use, interventional radiologists/cardiologists who wore aprons, nuclear medicine personnel and radiation oncologists exposed to high-energy photon radiation, and other workers. Standardized mortality ratio (SMR) analyses were performed. Cox proportional hazards models were used to estimate organ-specific radiation risks.

RESULTS

Overall, 11,433 deaths occurred (SMR 0.60; 95%CI 0.59,0.61), 126 from leukemia other than chronic lymphocytic leukemia (CLL), 850 from lung cancer, and 1654 from IHD. The mean duration of monitoring was 23.7 y. The excess relative rate (ERR) per 100 mGy was estimated as 0.10 (95% CI -0.34, 0.54) for leukemia other than CLL, 0.15 (0.02, 0.27) for lung cancer, and -0.10 (-0.27, 0.06) for IHD. The ERR for lung cancer was 0.16 (0.01, 0.32) among the 55,218 male workers and 0.09 (-0.19, 0.36) among the 53,801 female workers; a difference that was not statistically significant (p-value = 0.23).

CONCLUSIONS

Medical radiation workers were at increased risk for lung cancer that was higher among men than women, although this difference was not statistically significant. In contrast, the study of Japanese atomic bomb survivors exposed briefly to radiation in 1945 found females to be nearly 3 times the radiation risk of lung cancer compared with males on a relative scale. For medical workers, there were no statistically significant radiation associations with leukemia excluding CLL, IHD or other specific causes of death. Combining these data with other cohorts within the MPS, such as nuclear power plant workers and nuclear submariners, will enable more precise estimates of radiation risks at relatively low cumulative doses.

Suicide and other causes of death among Chernobyl cleanup workers from Estonia, 1986 - 2020: an update

Mortality was studied in a cohort of 4831 men from Estonia who participated in the environmental cleanup of the radioactively contaminated areas around Chernobyl in 1986-1991. Their mortality in 1986-2020 was compared with the mortality in the Estonian male population. A total of 1503 deaths were registered among the 4812 traced men. The all-cause standardized mortality ratio (SMR) was 1.04 (95% CI 0.99-1.09). All-cancer mortality was elevated (SMR 1.16, 95% CI 1.03-1.28). Radiation-related cancers were in excess (SMR 1.20, 95% CI 1.03-1.36); however, the excesses could be attributed to tobacco and alcohol consumption. For smoking-related cancers, the SMR was 1.20 (95% CI 1.06-1.35) and for alcohol-related cancers the SMR was 1.56 (95% CI 1.26-1.86). Adjusted relative risks (ARR) of all-cause mortality were increased among workers who stayed in the Chernobyl area ≥ 92 days (ARR 1.20, 95% CI 1.08-1.34), were of non-Estonian ethnicity (ARR 1.33, 95% CI 1.19-1.47) or had lower (basic or less) education (ARR 1.63, 95% CI 1.45-1.83). Suicide mortality was increased (SMR 1.31, 95% CI 1.05-1.56), most notably among men with lower education (ARR 2.24, 95% CI 1.42-3.53). Our findings provide additional evidence that unhealthy behaviors such as alcohol and smoking play an important role in shaping cancer mortality patterns among Estonian Chernobyl cleanup workers. The excess number of suicides suggests long-term psychiatric and substance use problems tied to Chernobyl-related stressors, i.e., the psychosocial impact was greater than any direct carcinogenic effect of low-dose radiation.

Summary of Radiation Research Society Online 67th Annual Meeting, Symposium on "Radiation and Circulatory Effects"

PURPOSE

This article summarizes a number of presentations from a session on "Radiation and Circulatory Effects" held during the Radiation Research Society Online 67^th Annual Meeting, October 3-6 2021.

MATERIALS AND METHODS

Different epidemiological cohorts were analyzed with various statistical means common in epidemiology. The cohorts included the one from the U.S. Million Person Study and the Canadian Fluoroscopy Cohort Study. In addition, one of the contributions in our article relies on results from analyses of the Japanese atomic bomb survivors, Russian emergency and recovery workers and cohorts of nuclear workers. The Canadian Fluoroscopy Cohort Study data were analyzed with a larger series of linear and nonlinear dose-response models in addition to the linear no-threshold (LNT) model.

RESULTS AND CONCLUSIONS

The talks in this symposium showed that low/moderate acute doses at low/moderate dose rates can be associated with an increased risk of CVD, although some of the epidemiological results for occupational cohorts are equivocal. The usually only limited availability of information on well-known risk factors for circulatory disease (e.g. smoking, obesity, hypertension, diabetes, physical activity) is an important limiting factor that may bias any observed association between radiation exposure and detrimental health outcome, especially at low doses. Additional follow-up and careful dosimetric and outcome assessment are necessary and more epidemiological and experimental research is required. Obtaining reliable information on other risk factors is especially important.

Radiation and CNS effects: summary of evidence from a recent symposium of the Radiation Research Society

This article summarizes a Symposium on 'Radiation risks of the central nervous system' held virtually at the 67th Annual Meeting of the Radiation Research Society, 3-6 October 2021. Repeated low-dose radiation exposure over a certain period could lead to reduced neuronal proliferation, altered neurogenesis, neuroinflammation and various neurological complications, including psychological consequences, necessitating further research in these areas. Four speakers from radiation biology, genetics and epidemiology presented the latest data from their studies seeking insights into this important topic. This symposium highlighted new and important directions for further research on mental health disorders, neurodegenerative conditions and cognitive impairment. Future studies will examine risks of mental and behavioral disorders and neurodegenerative diseases following protracted radiation exposures to better understand risks of occupational exposures as well as provide insights into risks from exposures to galactic cosmic rays.

Ionizing radiation exposure during adulthood and risk of developing central nervous system tumors: systematic review and meta-analysis

Many studies on ionizing radiation (IR) exposure during childhood have shown deleterious effects on the central nervous system (CNS), however results regarding adult exposure are inconsistent, and no systematic reviews have been performed. The objectives are to synthesize the findings and draw evidence-based conclusions from epidemiological studies on the risk of benign and malignant brain and CNS tumors in humans exposed to low-to-moderate doses (< 0.5 Gy) of IR during adulthood/young adulthood. A systematic literature search of four electronic databases, supplemented by a hand search, was performed to retrieve relevant epidemiological studies published from 2000 to 2022. Pooled excess relative risk (ERR_pooled) was estimated using a random effect model. Eighteen publications were included in the systematic review and twelve out of them were included in a meta-analysis. The following IR sources were considered: atomic bombs, occupational, and environmental exposures. No significant dose-risk association was found for brain/CNS tumors (ERR_pooled at 100 mGy = − 0.01; 95% CI: − 0.05, 0.04). Our systematic review and meta-analysis did not show any association between exposure to low-to-moderate doses of IR and risk of CNS tumors. Further studies with histological information and precise dose assessment are needed.

Low Dose and Non-Targeted Radiation Effects in Environmental Protection and Medicine-A New Model Focusing on Electromagnetic Signaling

The role of signalling in initiating and perpetuating effects triggered by deposition of ionising radiation energy in parts of a system is very clear. Less clear are the very early steps involved in converting energy to chemical and biological effects in non-targeted parts of the system. The paper aims to present a new model, which could aid our understanding of the role of low dose effects in determining ultimate disease outcomes. We propose a key role for electromagnetic signals resulting from physico-chemical processes such as excitation decay, and acoustic waves. These lead to the initiation of damage response pathways such as elevation of reactive oxygen species and membrane associated changes in key ion channels. Critically, these signalling pathways allow coordination of responses across system levels. For example, depending on how these perturbations are transduced, adverse or beneficial outcomes may predominate. We suggest that by appreciating the importance of signalling and communication between multiple levels of organisation, a unified theory could emerge. This would allow the development of models incorporating time, space and system level to position data in appropriate areas of a multidimensional domain. We propose the use of the term "infosome" to capture the nature of radiation-induced communication systems which include physical as well as chemical signals. We have named our model "the variable response model" or "VRM" which allows for multiple outcomes following exposure to low doses or to signals from low dose irradiated cells, tissues or organisms. We suggest that the use of both dose and infosome in radiation protection might open up new conceptual avenues that could allow intrinsic uncertainty to be embraced within a holistic protection framework.

Risk of Developing Non-Cancerous Central Nervous System Diseases Due to Ionizing Radiation Exposure during Adulthood: Systematic Review and Meta-Analyses

Background: High-dose ionizing radiation (IR) (>0.5 Gy) is an established risk factor for cognitive impairments, but this cannot be concluded for low-to-moderate IR exposure (<0.5 Gy) in adulthood as study results are inconsistent. The objectives are to summarize relevant epidemiological studies of low-to-moderate IR exposure in adulthood and to assess the risk of non-cancerous CNS diseases. Methods: A systematic literature search of four electronic databases was performed to retrieve relevant epidemiological studies published from 2000 to 2022. Pooled standardized mortality ratios, relative risks, and excess relative risks (ERR) were estimated with a random effect model. Results: Forty-five publications were included in the systematic review, including thirty-three in the quantitative meta-analysis. The following sources of IR-exposure were considered: atomic bomb, occupational, environmental, and medical exposure. Increased dose-risk relationships were found for cerebrovascular diseases incidence and mortality (ERRpooled per 100 mGy = 0.04; 95% CI: 0.03−0.05; ERRpooled at 100 mGy = 0.01; 95% CI: −0.00−0.02, respectively) and for Parkinson’s disease (ERRpooled at 100 mGy = 0.11; 95% CI: 0.06−0.16); Conclusions: Our findings suggest that adult low-to-moderate IR exposure may have effects on non-cancerous CNS diseases. Further research addressing inherent variation issues is encouraged.

Cancer risk following low doses of ionising radiation - Current epidemiological evidence and implications for radiological protection

Recent studies suggest that every year worldwide about a million patients might be exposed to doses of the order of 100 mGy of low-LET radiation, due to recurrent application of radioimaging procedures. This paper presents a synthesis of recent epidemiological evidence on radiation-related cancer risks from low-LET radiation doses of this magnitude. Evidence from pooled analyses and meta-analyses also involving epidemiological studies that, individually, do not find statistically significant radiation-related cancer risks is reviewed, and evidence from additional and more recent epidemiological studies of radiation exposures indicating excess cancer risks is also summarized. Cohorts discussed in the present paper include Japanese atomic bomb survivors, nuclear workers, patients exposed for medical purposes, and populations exposed environmentally to natural background radiation or radioactive contamination. Taken together, the overall evidence summarized here is based on studies including several million individuals, many of them followed-up for more than half a century. In summary, substantial evidence was found from epidemiological studies of exposed groups of humans that ionizing radiation causes cancer at acute and protracted doses above 100 mGy, and growing evidence for doses below 100 mGy. The significant radiation-related solid cancer risks observed at doses of several 100 mGy of protracted exposures (observed, for example, among nuclear workers) demonstrate that doses accumulated over many years at low dose rates do cause stochastic health effects. On this basis, it can be concluded that doses of the order of 100 mGy from recurrent application of medical imaging procedures involving ionizing radiation are of concern, from the viewpoint of radiological protection.

A million persons, a million dreams: a vision for a national center of radiation epidemiology and biology

BACKGROUND

Epidemiologic studies of radiation-exposed populations form the basis for human safety standards. They also help shape public health policy and evidence-based health practices by identifying and quantifying health risks of exposure in defined populations. For more than a century, epidemiologists have studied the consequences of radiation exposures, yet the health effects of low levels delivered at a low-dose rate remain equivocal.

MATERIALS AND METHODS

The Million Person Study (MPS) of U.S. Radiation Workers and Veterans was designed to examine health effects following chronic exposures in contrast with brief exposures as experienced by the Japanese atomic bomb survivors. Radiation associations for rare cancers, intakes of radionuclides, and differences between men and women are being evaluated, as well as noncancers such as cardiovascular disease and conditions such as dementia and cognitive function. The first international symposium, held November 6, 2020, provided a broad overview of the MPS. Representatives from four U.S. government agencies addressed the importance of this research for their respective missions: U.S. Department of Energy (DOE), the Centers for Disease Control and Prevention (CDC), the U.S. Department of Defense (DOD), and the National Aeronautics and Space Administration (NASA). The major components of the MPS were discussed and recent findings summarized. The importance of radiation dosimetry, an essential feature of each MPS investigation, was emphasized.

RESULTS

The seven components of the MPS are DOE workers, nuclear weapons test participants, nuclear power plant workers, industrial radiographers, medical radiation workers, nuclear submariners, other U.S. Navy personnel, and radium dial painters. The MPS cohorts include tens of thousands of workers with elevated intakes of alpha particle emitters for which organ-specific doses are determined. Findings to date for chronic radiation exposure suggest that leukemia risk is lower than after acute exposure; lung cancer risk is much lower and there is little difference in risks between men and women; an increase in ischemic heart disease is yet to be seen; esophageal cancer is frequently elevated but not myelodysplastic syndrome; and Parkinson's disease may be associated with radiation exposure.

CONCLUSIONS

The MPS has provided provocative insights into the possible range of health effects following low-level chronic radiation exposure. When the 34 MPS cohorts are completed and combined, a powerful evaluation of radiation-effects will be possible. This final article in the MPS special issue summarizes the findings to date and the possibilities for the future. A National Center for Radiation Epidemiology and Biology is envisioned.

Mortality from Leukemia, Cancer and Heart Disease among U.S. Nuclear Power Plant Workers, 1957-2011

BACKGROUND

The aim of the Million Person Study (MPS) of Low Dose Health Effects is to examine the level of radiation risk for chronic exposures received gradually over time and not acutely as was the case for the Japanese atomic bomb survivors. Nuclear power plant (NPP) workers comprise nearly 15 percent of the MPS. Leukemia, selected cancers, Parkinson's disease, ischemic heart disease (IHD) and other causes of death are evaluated.

METHODS AND MATERIAL

The U.S. Nuclear Regulatory Commission's Radiation Exposure Information and Reporting System (REIRS) and the Landauer, Inc. dosimetry databases identified 135,193 NPP workers first monitored 1957-1984. Annual personal dose equivalents [Hp(10)] were available for each worker. Radiation records from all places of employment were sought. Vital status was determined through 2011. Mean absorbed doses to red bone marrow (RBM), esophagus, lung, colon, brain and heart were estimated by adjusting the recorded Hp(10) for each worker by scaling factors, accounting for exposure geometry and energy of the incident gamma radiation. Standardized mortality ratios (SMR) were calculated. Radiation risks were estimated using Cox proportional hazards models.

RESULTS

Nearly 50% of workers were employed for more than 20 years. The mean duration of follow-up was 30.2 y. Overall, 29,076 total deaths occurred, 296 from leukemia other than chronic lymphocytic leukemia (CLL), 3,382 from lung cancer, 140 from Parkinson's disease and 5,410 from IHD. The mean dose to RBM was 37.9 mGy (maximum 1.0 Gy; percent >100 mGy was 9.2%), 43.2 mGy to lung, 43.7 mGy to colon, 33.2 mGy to brain, and 43.9 mGy to heart. The SMRs (95% CI) were 1.06 (0.94;1.19) for leukemia other than CLL, 1.10 (1.07;1.14) for lung cancer, 0.90 (0.76;1.06) for Parkinson's disease, and 0.80 (0.78; 0.82) for IHD. The excess relative risk (ERR) per 100 mGy for leukemia other than CLL was 0.15 (90% CI 0.001; 0.31). For all solid cancers the ERR per 100 mGy (95% CI) was 0.01 (-0.03; 0.05), for lung cancer -0.04 (-0.11; 0.02), for Parkinson's disease 0.24 (-0.02; 0.50), and for IHD -0.01 (-0.06; 0.04).

CONCLUSION

Prolonged exposure to radiation increased the risk of leukemia other than CLL among NPP workers. There was little evidence for a radiation-association for all solid cancers, lung cancer or ischemic heart disease. Increased precision will be forthcoming as the different cohorts within the MPS are combined, such as industrial radiographers and medical radiation workers who were assembled and evaluated in like manner.

Mortality among workers at the Los Alamos National Laboratory, 1943-2017

BACKGROUND

During World War II (WWII), the Manhattan Engineering District established a secret laboratory in the mountains of northern New Mexico. The mission was to design, construct and test the first atomic weapon, nicknamed 'The Gadget' that was detonated at the TRINITY site in Alamogordo, NM. After WWII, nuclear weapons research continued, and the laboratory became the Los Alamos National Laboratory (LANL).

MATERIALS AND METHODS

The mortality experience of 26,328 workers first employed between 1943 and 1980 at LANL was determined through 2017. Included were 6157 contract workers employed by the ZIA Company. Organ dose estimates for each worker considered all sources of exposure, notably photons, neutrons, tritium, ²³⁸Pu and ²³⁹Pu. Vital status determination included searches within the National Death Index, Social Security Administration and New Mexico State Mortality Files. Standardized Mortality Ratios (SMR) and Cox regression models were used in the analyses.

RESULTS

Most workers (55%) were hired before 1960, 38% had a college degree, 25% were female, 81% white, 13% Hispanic and 60% had died. Vital status was complete, with only 0.1% lost to follow-up. The mean dose to the lung for the 17,053 workers monitored for radiation was 28.6 weighted-mGy (maximum 16.8 weighted-Gy) assuming a Dose Weighting Factor of 20 for alpha particle dose to lung. The Excess Relative Risk (ERR) at 100 weighted-mGy was 0.01 (95%CI -0.02, 0.03; n = 839) for lung cancer. The ERR at 100 mGy was -0.43 (95%CI -1.11, 0.24; n = 160) for leukemia other than chronic lymphocytic leukemia (CLL), -0.06 (95%CI -0.16, 0.04; n = 3043) for ischemic heart disease (IHD), and 0.29 (95%CI 0.02, 0.55; n = 106) for esophageal cancer. Among the 6499 workers with measurable intakes of plutonium, an increase in bone cancer (SMR 2.44; 95%CI 0.98, 5.03; n = 7) was related to dose. The SMR for berylliosis was significantly high, based on 4 deaths. SMRs for Hispanic workers were significantly high for cancers of the stomach and liver, cirrhosis of the liver, nonmalignant kidney disease and diabetes, but the excesses were not related to radiation dose.

CONCLUSIONS

There was little evidence that radiation increased the risk of lung cancer or leukemia. Esophageal cancer was associated with radiation, and plutonium intakes were linked to an increase of bone cancer. IHD was not associated with radiation dose. More precise evaluations will await the pooled analysis of workers with similar exposures such as at Rocky Flats, Savannah River and Hanford.

Risk of Prostate Cancer Incidence among Atomic Bomb Survivors: 1958-2009

Epidemiological evidence for a radiation effect on prostate cancer risk has been inconsistent and largely indicative of no or little effect. Here we studied prostate cancer incidence among males of the Life Span Study cohort of atomic bomb survivors in a follow-up from 1958 to 2009, eleven years more than was previously reported. During this period there were 851 incident cases of prostate cancer among 41,544 male subjects, doubling the total number of cases in the cohort. More than 50% of the cases were diagnosed among those who were less than 20 years of age at the time of the bombings and who were at, or near, the ages of heightened prostate cancer risks during the last decade of follow-up. In analyses of the radiation dose response using Poisson regression methods, we used a baseline-rate model that allowed for calendar period effects corresponding to the emergence of prostate-specific antigen screening in the general population as well as effects of attained age and birth cohort. The model also allowed for markedly increased baseline rates among the Adult Health Study participants between 2005 and 2009, a period during which a prostate-specific antigen test was included in Adult Health Study biennial health examinations. We found a significant linear dose response with an estimated excess relative risk (ERR) per Gy of 0.57 (95% CI: 0.21, 1.00, P = 0.001). An estimated 40 of the observed cases were attributed to radiation exposure from the bombings. There was a suggestion of the ERR decreasing with increasing age at exposure (P = 0.09). We found no indication of effects of smoking, alcohol consumption and body mass index on the baseline risk of prostate cancer. The observed dose response strengthens the evidence of a radiation effect on the risk of prostate cancer incidence in the atomic bomb survivors.

Radiation Risks for the Incidence of Kidney, Bladder and Other Urinary Tract Cancers: 1958-2009

As part of the recent series of articles to create a comprehensive description of the radiation risks of solid cancer incidence after ionizing radiation exposure, based on the atomic bomb survivors' Life Span Study (LSS), this work focuses on the risks of urinary tract cancer (UTC) and kidney cancer. Analyses covered a 52-year period of follow-up, through 2009, among 105,444 eligible survivors who were alive and cancer free in 1958. This represents an additional 11 years of follow-up since the last comprehensive report, with a total of 3,079,502 person-years. We observed 790 UTC and 218 kidney cancer cases. Adjusted for smoking, there was a strong linear radiation dose response for UTC. The sex-averaged excess relative risk per 1 Gy (ERR/Gy) was 1.4 (95% confidence interval, CI: 0.82 to 2.1). Both males and females showed significantly increased ERRs/Gy with female point estimates at a factor of 3.4 (95% CI: 1.4 to 8.6) greater than male estimates. UTC radiation risks were largely unmodified by age at exposure or attained age. The attributable fraction of UTC to radiation exposure was approximately 18% while that attributed to smoking was 48%. Kidney cancer showed an increased ERR due to smoking (0.56 per 50 pack-years; 95% CI -0.007 to 1.6; P = 0.054), but we did not observe any strong associations of kidney cancer with radiation exposure, although sex-specific dose responses were found to be statistically different.

Low- and moderate-dose non-cancer effects of ionizing radiation in directly exposed individuals, especially circulatory and ocular diseases: a review of the epidemiology

PURPOSE

There are well-known correlations between high and moderate doses (>0.5 Gy) of ionizing radiation exposure and circulatory system damage, also between radiation and posterior subcapsular cataract. At lower dose correlations with circulatory disease are emerging in the Japanese atomic bomb survivors and in some occupationally exposed groups, and are still to some extent controversial. Heterogeneity in excess relative risks per unit dose in epidemiological studies at low (<0.1 Gy) and at low-moderate (>0.1 Gy, <0.5 Gy) doses may result from confounding and other types of bias, and effect modification by established risk factors. There is also accumulating evidence of excess cataract risks at lower dose and low dose rate in various cohorts. Other ocular endpoints, specifically glaucoma and macular degeneration have been little studied. In this paper, we review recent epidemiological findings, and also discuss some of the underlying radiobiology of these conditions. We briefly review some other types of mainly neurological nonmalignant disease in relation to radiation exposure.

CONCLUSIONS

We document statistically significant excess risk of the major types of circulatory disease, specifically ischemic heart disease and stroke, in moderate- or low-dose exposed groups, with some not altogether consistent evidence suggesting dose-response non-linearity, particularly for stroke. However, the patterns of risk reported are not straightforward. We also document evidence of excess risks at lower doses/dose-rates of posterior subcapsular and cortical cataract in the Chernobyl liquidators, US Radiologic Technologists and Russian Mayak nuclear workers, with fundamentally linear dose-response. Nuclear cataracts are less radiogenic. For other ocular endpoints, specifically glaucoma and macular degeneration there is very little evidence of effects at low doses; radiation-associated glaucoma has been documented only for doses >5 Gy, and so has the characteristics of a tissue reaction. There is some evidence of neurological detriment following low-moderate dose (∼0.1-0.2 Gy) radiation exposure in utero or in early childhood.

Ionising radiation as a risk factor for lymphoma: a review

The ability of ionising radiation to induce lymphoma is unclear. Here, we present a narrative review of epidemiological evidence of the risk of lymphoma, including chronic lymphocytic leukaemia (CLL) and multiple myeloma (MM), among various exposed populations including atomic bombing survivors, industrial and medical radiation workers, and individuals exposed for medical purposes. Overall, there is a suggestion of a positive dose-dependent association between radiation exposure and lymphoma. The magnitude of this association is highly imprecise, however, with wide confidence intervals frequently including zero risk. External comparisons tend to show similar incidence and mortality rates to the general population. Currently, there is insufficient information on the impact of age at exposure, high versus low linear energy transfer radiation, external versus internal or acute versus chronic exposures. Associations are stronger for males than females, and stronger for non-Hodgkin lymphoma and MM than for Hodgkin lymphoma, while the risk of radiation-induced CLL may be non-existent. This broad grouping of diverse diseases could potentially obscure stronger associations for certain subtypes, each with a different cell of origin. Additionally, the classification of malignancies as leukaemia or lymphoma may result in similar diseases being analysed separately, while distinct diseases are analysed in the same category. Uncertainty in cell of origin means the appropriate organ for dose response analysis is unclear. Further uncertainties arise from potential confounding or bias due to infectious causes and immunosuppression. The potential interaction between radiation and other risk factors is unknown. Combined, these uncertainties make lymphoma perhaps the most challenging malignancy to study in radiation epidemiology.

Ionizing Radiation and Translation Control: A Link to Radiation Hormesis?

Protein synthesis, or mRNA translation, is one of the most energy-consuming functions in cells. Translation of mRNA into proteins is thus highly regulated by and integrated with upstream and downstream signaling pathways, dependent on various transacting proteins and cis-acting elements within the substrate mRNAs. Under conditions of stress, such as exposure to ionizing radiation, regulatory mechanisms reprogram protein synthesis to translate mRNAs encoding proteins that ensure proper cellular responses. Interestingly, beneficial responses to low-dose radiation exposure, known as radiation hormesis, have been described in several models, but the molecular mechanisms behind this phenomenon are largely unknown. In this review, we explore how differences in cellular responses to high- vs. low-dose ionizing radiation are realized through the modulation of molecular pathways with a particular emphasis on the regulation of mRNA translation control.