Low radon exposure and mortality among Jouac uranium miners An update of the French cohort (1946-2007)

International audienceAfter the extension of the French cohort of uranium miners with the inclusion of workers employed in the Jouac mines, this article seeks to describe the new Jouac cohort and to estimate mortality risks, as well as to quantify their relation to radon exposure in this extended cohort. The Jouac cohort includes 458 miners hired by the Société des Mines de Jouac between 1957 and 2001. There is no measurement of radon exposure before 1978 and so no data were available. Consequently, only the post-1977 Jouac cohort (n = 314) has been included in the French cohort, creating an extended cohort of 5400 French uranium miners followed up from 1946 to 2007. Mortality analyses computed the standardised mortality ratios (SMRs). Excess relative risks (ERRs) were assessed using Poisson regression models. No evidence of a significant excess risk of overall mortality (n = 66, SMR = 0.93; 95% CI = 0.72-1.19) or any specific mortality was observed in the Jouac cohort. In the extended cohort, overall mortality did not increase, but a significant excess of deaths was observed for all cancers (SMR = 1.11, 95% CI = 1.03-1.19), lung cancer (SMR = 1.32, 95% CI = 1.14-1.51), and kidney cancer (SMR = 1.58, 95% CI = 1.01-2.35). Cumulative exposure to radon was 3.9 working level month (WLM) and 35.1 WLM in the post-1977 Jouac and extended cohorts, respectively. Cumulative radon exposure was significantly associated with an excess risk of death from lung cancer (ERR/100 WLM = 0.73, 95% CI = 0.32-1.33) and from cerebrovascular diseases (ERR/100 WLM = 0.42 95% CI = 0.04-1.04). In conclusion, the Jouac cohort is still a young cohort and its inclusion leads to slight modifications compared to previous analyses of the French cohort. The already known relation between radon exposure and lung cancer death as well as the excess risk of death from cerebrovascular diseases persisted in the extended cohort. © 2017 IOP Publishing Ltd

Mortality from Circulatory System Diseases among French Uranium Miners A Nested Case-Control Study

International audienceA significant association has been observed between radon exposure and cerebrovascular disease (CeVD) mortality among French uranium miners, but risk factors for circulatory system diseases (CSD) have not been previously considered. We conducted new analyses in the recently updated (through 2007) French cohort of uranium miners (n 5,086), which included 442 deaths from CSD, 167 of them from ischemic heart disease (IHD) and 105 from CeVD. A nested case-control study was then set up to collect and investigate the influence of these risk factors on the relationships between mortality from CSD and occupational external gamma ray and internal ionizing radiation exposure (radon and long-lived radionuclides) in this updated cohort. The nested case-control study included miners first employed after 1955, still employed in 1976 and followed up through 2007. Individual information about CSD risk factors was collected from medical files for the 76 deaths from CSD (including 26 from IHD and 16 from CeVD) and 237 miners who had not died of CSD by the end of follow-up. The exposure-risk relationships were assessed with a Cox proportional hazard model weighted by the inverse sampling probability. A significant increase in all CSD and CeVD mortality risks associated with radon exposure was observed in the total cohort [hazard ratios HRCSD/100 working level months (WLM) = 1.11, 95% confidence interval (1.01; 1.22) and HRCeVD/100 WLM = 1.25 (1.09; 1.43), respectively]. A nonsignificant exposure-risk relationship was observed for every type of cumulative ionizing radiation exposure and every end point [e.g., HRCSD/100WLM = 1.43 (0.71; 2.87)]. The adjustment for each CSD risk factor did not substantially change the exposure-risk relationships. When the model was adjusted for overweight, hypertension, diabetes, hypercholesterolemia and smoking status, the HR/100WLM for CSD, for example, was equal to 1.21 (0.54; 2.75); and when it was adjusted for risk factors selected with the Akaike information criterion, it was equal to 1.44 (0.66; 3.14). To our knowledge, this is the first study to use a uranium miner cohort to consider the major standard CSD risk factors in assessing the relationships between ionizing radiation exposure and the risk of death from these diseases. These results suggest that the significant relationship between CeVD risk and radon exposure observed in the total French cohort is probably not affected by the CSD risk factors. Extending the collection of information about CSD risk factors to a larger subsample would be useful to confirm this result. ©2015 by Radiation Research Society

Mortality in the French cohort of nuclear workers

Populations of nuclear workers are particularly relevant to study health effects of protracted exposures to low doses at low dose-rates of ionizing radiation. In France, a cohort of nuclear workers employed by the Commissariat à l'énergie atomique et aux énergies alternatives (CEA), AREVA Nuclear Cycle (AREVA NC), or Électricité de France (EDF), and badge-monitored for external radiation exposure, has been followed-up for several decades. Annual exposure to penetrating photons was reconstructed for each worker. Standardized mortality ratios were calculated using national mortality rates as the reference. Estimates of radiation dose-mortality associations were obtained using linear excess relative risk models. Mortality of 59 004 workers was followed-up between 1968 and 2004, for an average of 25 years. The mean cumulative photon Hp(10) dose was 18.4 mSv in the whole cohort (median value: 2.1 mSv) and 25.7 mSv among exposed workers. At the end of the follow-up, workers were 56 years old on average and 6310 workers had died. A strong healthy worker effect was observed. Estimated dose-risk relationships were consistent with those from other worker studies for all solid cancers and leukaemia excluding chronic lymphocytic leukaemia, but remained associated to a large uncertainty. This cohort is the most informative study ever conducted in France among nuclear workers

Solid cancer mortality associated with chronic external radiation exposure at the french atomic energy commission and nuclear fuel company

Studies of nuclear workers make it possible to directly quantify the risks associated with ionizing radiation exposure at low doses and low dose rates. Studies of the CEA (Commissariat l'Energie Atomique) and AREVA Nuclear Cycle (AREVA NC) cohort, currently the most informative such group in France, describe the long-term risk to nuclear workers associated with external exposure. Our aim is to assess the risk of mortality from solid cancers among CEA and AREVA NC nuclear workers and its association with external radiation exposure. Standardized mortality ratios (SMRs) were calculated and internal Poisson regressions were conducted, controlling for the main confounding factors sex, attained age, calendar period, company and socioeconomic status (SES). During the period 19682004, there were 2,035 solid cancers among the 36,769 CEA-AREVA NC workers. Cumulative external radiation exposure was assessed for the period 19502004, and the mean cumulative dose was 12.1 mSv. Mortality rates for all causes and all solid cancers were both significantly lower in this cohort than in the general population. A significant excess of deaths from pleural cancer, not associated with cumulative external dose, was observed, probably due to past asbestos exposure. We observed a significant excess of melanoma, also unassociated with dose. Although cumulative external dose was not associated with mortality from all solid cancers, the central estimated excess relative risk (ERR) per Sv of 0.46 for solid cancer mortality was higher than the 0.26 calculated for male Hiroshima and Nagasaki A-bomb survivors 50 years or older and exposed at the age of 30 years or older. The modification of our results after stratification for SES demonstrates the importance of this characteristic in occupational studies, because it makes it possible to take class-based lifestyle differences into account, at least partly. These results show the great potential of a further joint international study of nuclear workers, which should improve knowledge about the risks associated with chronic low doses and provide useful risk estimates for radiation protection. © 2011 by Radiation Research Society

Mortality analyses in the updated French cohort of uranium miners (1946–2007)

International audiencePurpose The objectives are to analyze mortality risks in the extended follow-up of the French uranium miners’ cohort and to examine their potential relation to occupational exposure to ionizing radiation (IR). Methods The total cohort includes 5,086 uranium miners employed in the CEA-COGEMA group and followed up from 1946 to 2007. Vital status, causes of death, and cumulative radon exposures were recorded. The post-55 subcohort includes 3,377 miners first employed after 1955, for whom long-lived radionuclides (LLR) and external gamma-ray exposure were also recorded. External mortality analyses were performed by computing standardized mortality ratios (SMR). Excess relative risks (ERRs) due to IR exposures were estimated from Poisson regression models. Results The miners included in the total cohort were followed up for 35.4 years and exposed to 36.6 working level months (WLM) on average. There was no evidence of a difference in overall mortality between miners and the general French male population. Miners had a statistically significant excess mortality rate from lung cancer (SMR = 1.34 [95 % CI 1.16–1.53]) and from kidney cancer (SMR = 1.60 [1.03–2.39]). Cumulative radon exposure was significantly associated with lung cancer risk (ERR/100 WLM = 0.71 [0.31–1.30]) and cerebrovascular risk (ERR/100 WLM = 0.41 [0.04–1.03]). In the post-55 subcohort, this excess mortality from lung cancer remained associated with exposure to radon, and also with exposure to LLR and external gamma rays. Conclusions The analyses in the extended follow-up strengthen the results previously observed among French uranium miners about their excess risk of mortality and its association with their occupational IR exposure. © 2014, Springer-Verlag Berlin Heidelberg

Multifactorial study of the risk of lung cancer among French uranium miners: Radon, smoking and silicosis

This case-control study nested in the French cohort of uranium miners provides an opportunity to take account of silicosis and smoking in the assessment of the relation between radon and lung cancer. The study includes 100 miners who died of lung cancer and 500 matched controls born within the same period of birth and of the same age at the time of death of the matching case. Data on radon exposure are obtained from individual monitoring of the miners, and data on smoking come from medical records and interviews. To identify cases of silicosis among the 600 miners surveyed, appraisals carried out as part of the compensation process for occupational diseases are used. Statistical analyses are based on a conditional logistic regression, and the linear model for excess relative risk was used to model the risk of death due to lung cancer according to cumulative radon exposure. The percentage of missing data on silicotic status is less than 20%. The study reveals a significant association between the relative risk of lung cancer and silicosis (ORsilicosis = 3.6; 95% CI: 1.4-8.9), and the relation between radon and lung cancer persists after adjusting for smoking and silicotic status (ERRradon per WLM = 1.0%; 95% CI: 0.1-3.5%). Radon, cigarette smoking and silicotic status appear to be three factors that each have a specific effect on the risk of lung cancer. This study reminds us of the complexity involved in assessing occupational risks in the case of multiple sources of exposure. Copyright © 2009 Health Physics Society

Chest X-ray screening examinations among French uranium miners Exposure estimation and impact on radon-associated lung cancer risk

International audienceBackground Medical surveillance of uranium miners can include periodic chest X-ray examinations. This study aimed to assess the X-ray exposure due to occupational health monitoring in the French cohort of uranium miners, and to test whether consideration of this additional radiation exposure impacts the excess risk of lung cancer death associated with radon exposure. Method X-ray exposure due to occupational health monitoring was estimated retrospectively based on review of a sample of miners' medical records and bibliographic data. Four exposure scenarios were designed, differing in their assumptions about the type of procedures performed, their frequency, and the lung dose delivered. Radon exposure and lung doses from exposure to α-particle emitters and external γ rays have previously been individually assessed. Exposure-risk and dose-risk relations were estimated by Poisson regression with a linear excess relative risk (ERR) model. Results The cohort included 5086 miners with a mean follow-up duration of 30.1 years. The mean number of chest X-ray examinations ranged from 15.1 in the lowest to 34 in the highest-exposure scenario, and produced a mean cumulative lung dose ranging from 4.6 to 34.2 mGy. The role of occupation-related imaging screening X-ray procedures in total equivalent lung dose appeared insignificant compared to α-emitter exposure. X-ray exposure was not associated with lung cancer mortality risk. The ERR associated with radon remained significantly positive when X-ray exposure was included in the multivariate analysis. Conclusions X-ray exposure did not confound the exposure-risk relation between radon and lung cancer

The influence of multiple types of occupational exposure to Radon, Gamma Rays and Long-Lived Radionuclides on Mortality Risk in the French \textquotedblpost-55\textquotedbl Sub-cohort of Uranium Miners: 1956-1999

The adverse health effects of radon on uranium miners, especially on their lungs, are well documented, but few studies have considered the effects of other radiation exposures. This study examined the mortality risks associated with exposure to radon, external \textgreekg rays and long-lived radionuclides (LLR) in the French \textquotedblpost-55\textquotedbl sub-cohort, which includes uranium miners first employed between 1956 and 1990 for whom all three types of exposure were assessed individually. Exposurerisk relationships were estimated with linear excess relative risk models and a 5-year lag time. The post-55 sub-cohort includes 3377 miners, contributing 89,405 person-years, followed up through the end of 1999 with a mean follow-up of 26.5 years. Mean cumulative exposure was 17.8 WLM for radon, 54.7 mSv for \textgreekg rays, and 1,632 Bq.m -3.h for LLR. Among the 611 deaths observed, 66 were due to lung cancer. Annual individual exposures were significantly correlated. Increased mortality was observed for lung cancer (SMR = 1.30; 95% CI: 1.01, 1.65) and for brain and central nervous system (CNS) cancer (SMR = 2.00; 95% CI: 1.09, 3.35). Cumulative exposure to radon, \textgreekg rays and LLR was associated only with a significant risk of lung cancer. These new results could suggest an association between lung cancer and exposure to \textgreekg rays and LLR. They must nonetheless be interpreted with caution because of the correlation between the types of exposure. The calculation of organ doses received by each of these exposures would reduce the collinearity. © 2011 by Radiation Research Society

Mortality from circulatory system diseases and low-level radon exposure in the French cohort study of uranium miners, 1946-1999

cited By 18Objectives: The few studies examining the risk of circulatory system diseases (CSD) associated with ionizing radiation have reported inconsistent results. Radon, a known pulmonary carcinogen, emits ionizing radiation. The aim of this study was to examine CSD mortality in a French cohort of uranium miners and evaluate the plausibility of an association with radon exposure. Methods: The cohort included men employed as uranium miners for ≥1 year between 1946-1990. We obtained vital status and cause of death from national registers and reconstructed radon exposure for each year. Exposure - risk relations were estimated with a linear excess relative risk (ERR) model using a 5-year lag time. Results: The cohort comprised 5086 miners, followed up for a mean duration of 30.1 years. The average cumulative exposure of the radon-exposed miners was 36.6 working level months (WLM). A total of 1411 deaths were observed, including 319 deaths due to CSD. No excess risk was found for this overall cause of death. A significant positive trend was observed between deaths from cerebrovascular diseases (CeVD) and cumulative radon exposure, together with a significant ERR per 100 WLM [ERR per 100 WLM 0.49, 95% confidence interval (95% CI) 0.07-1.23)]. Hard physical activity was identified as a potential modifying factor of the exposure-risk relation. Conclusions: For the first time in a cohort of uranium miners, our results suggest an association between CeVD mortality and cumulative radon exposure. Due to a lack of data, which limited our ability to assess possible confounding by cardiovascular risk factors, these findings should be interpreted with caution