Analysis of mortality in a pooled cohort of Canadian and German uranium processing workers with no mining experience.

PurposeLong-term health risks of occupational exposures to uranium processing were examined to better understand potential differences with uranium underground miners and nuclear reactor workers.MethodsA cohort study of mortality of workers from Port Hope, Canada (1950-1999) and Wismut, Germany (1946-2008) employed in uranium milling, refining, and processing was conducted. Poisson regression was used to evaluate the association between cumulative exposures to radon decay products (RDP) and gamma-rays and causes of death potentially related to uranium processing.ResultsThe pooled cohort included 7431 workers (270,201 person-years of follow-up). Mean RDP exposures were lower than in miners while gamma-ray doses were higher than in reactor workers. Both exposures were highly correlated (weighted rho = 0.81). Radiation risks of lung cancer and cardiovascular diseases (CVD) in males were increased but not statistically significant and compatible with risks estimated for miners and reactor workers, respectively. Higher RDP-associated CVD risks were observed for exposures 5-14 years prior to diagnosis compared to later exposures and among those employed <5 years. Radiation risks of solid cancers excluding lung cancer were increased, but not statistically significant, both for males and females, while all other causes of death were not associated with exposures.ConclusionsIn the largest study of uranium processing workers to systematically examine radiation risks of multiple outcomes from RDP exposures and gamma-rays, estimated radiation risks were compatible with risks reported for uranium miners and nuclear reactor workers. Continued follow-up and pooling with other cohorts of uranium processing workers are necessary for future comparisons with other workers of the nuclear fuel cycle

Occupational Exposure to Hydrazine and Subsequent Risk of Lung Cancer: 50-Year Follow-Up

Hydrazine is carcinogenic in animals, but there is inadequate evidence to determine if it is carcinogenic in humans. This study aimed to evaluate the association between hydrazine exposure and the risk of lung cancer.The cause specific mortality rates of a cohort of 427 men who were employed at an English factory that produced hydrazine between 1945 and 1971 were compared with national mortality rates.By the end of December 2012 205 deaths had occurred. For men in the highest exposure category with greater than two years exposure and after more than ten years since first exposure the relative risks compared with national rates were: 0.85 (95% CI: 0.18-2.48) for lung cancer, 0.61 (95% CI: 0.07-2.21) for cancers of the digestive system, and 0.44 (95% CI: 0.05-1.57) for other cancers.After 50 years of follow up, the results provide no evidence of an increased risk of death from lung cancer or death from any other cause

Etude épidémiologique des travailleurs du cycle du combustible nucléaire et analyse des effets sanitaires des composés uranifères en fonction de leur solubilité

Le lien entre l’exposition externe aux rayonnements γ et la mortalité par leucémie, par cancers solides et possiblement par maladies de l’appareil circulatoire (CSD) a fait l’objet de nombreuses études. En revanche, les risques sanitaires après contamination interne sont mal connus, et plus particulièrement en ce qui concerne l’inhalation de composés uranifères pouvant présenter des propriétés physico-chimiques (PCP) diverses (solubilité, isotopie etc…).L’objectif principal de mon travail de thèse a été d’étudier le risque de mortalité par maladies cancéreuses et non-cancéreuses chez des travailleurs du cycle du combustible français. La thèse était composée de trois axes : (1) revue critique de la littérature concernant l’impact l’uranium sur la mortalité ; (2) analyse de la mortalité dans la cohorte des travailleurs impliqués dans l’étape d’enrichissement ; (3) analyse de la relation entre la mortalité par CSD et la dose interne due à l’uranium chez les travailleurs d’AREVA NC Pierrelatte.Nous avons mis en place une cohorte de 4688 travailleurs impliqués dans l’étape d’enrichissement de l’uranium, suivi entre 1968 et 2008 pour étudier les risques associés à l’exposition à l’uranium très soluble. L’exposition annuelle de chaque travailleur a été reconstruite à partir de matrices emplois-expositions (JEM) et des données de surveillance radiologique pour les produits suivants : uranium, irradiation externe γ, nuisances non-radiologiques (trichloréthylène, chaleur, bruit). Au cours du suivi, 131161 personnes-années ont été cumulées et 21% de travailleurs sont décédés. L’analyse des ratios standardisés de mortalité (SMR) a montré un fort effet du travailleur sain (SMR toutes causes 0,69, intervalle de confiance (CI) à 95% de 0,65 à 0,74 ; n=1010). L’exposition interne à l’uranium et à la dose externe γ n’apparaissaient pas associées significativement à aucune des causes de mortalité considérées. Une tendance à la diminution du risque a été observée avec l’exposition à l’uranium pour la mortalité par cancer du poumon et par cancers lymphohématopoïétiques.Une analyse antérieure de la cohorte des travailleurs d’AREVA NC Pierrelatte avait suggéré une association entre l’exposition interne due à l’uranium et la mortalité par CSD. Une étude cas-témoins nichée a été mise en place pour analyser la relation dose-réponse et ajuster sur les facteurs de risque (tabagisme, pression artérielle, indice de masse corporelle, cholestérol, glycémie) recueillis à partir des dossiers médicaux. Cette étude a inclus 102 cas de CSD et 416 témoins appariés sur l’âge atteint, le sexe, la période de naissance et le statut socio-professionnel. Les doses absorbées ont été estimées en tenant compte des profils de solubilité des composés uranifères extraits de la JEM. La mortalité a été analysée par régression logistique conditionnelle. Une association positive mais associée à une large incertitude a été observée (Excess Odds Ratio 0,2 par 1 mGy, CI à 95% de 0,004 à 0,5). L’ajustement sur les facteurs confondants n’a pas modifié cette relation.Par rapport aux études précédentes, notre travail a plusieurs atouts méthodologiques : considération des PSC de l’uranium, calcul de la dose aux organes et ajustement sur les facteurs de confusion potentiels (exposition non-radiologique, facteurs de risque des CSD). L’absence d’association avec l’exposition à des composés uranifères très solubles peut s’interpréter par une élimination efficace de l’uranium par l’organisme. L’analyse de l’étude cas-témoins nichée prenant en compte les principaux facteurs de risque de CSD retrouve l’association avec le risque de CSD observée antérieurement. Les travaux futurs devraient se concentrer sur l’impact des incertitudes associées à l’estimation de la dose interne, la nature de l’association entre CSD et radiation et l’analyse de la relation temporelle entre l’exposition aux radiations et les facteurs de risque de CSD.External γ-radiation exposure has been shown to be associated with mortality risk due to leukemia, solid cancer, and, possibly, circulatory diseases (CSD). By contrast, little information is available on health risks following the internal contamination, especially the inhalation of uranium compounds, especially with respect to their physicochemical properties (PCP), such as solubility, isotopic composition and others.The aim of this PhD thesis was to estimate mortality risk of cancer and non-cancer diseases in French nuclear fuel cycle workers and was composed of three objectives: (1) systematic literature review of the impact of uranium on mortality, (2) analysis of cancer and non-cancer mortality in the cohort of uranium enrichment workers, (3) assessment of the relationship between CSD mortality and internal uranium dose in AREVA NC Pierrelatte workers.To study the mortality risk associated with exposure to rapidly soluble uranium compounds, we set up a cohort of 4,688 uranium enrichment workers with follow-up between 1968 and 2008. Individual annual exposure to uranium, external γ-radiation, and other non-radiological hazards (trichloroethylene, heat, and noise) were reconstructed from job-exposure matrixes (JEM) and dosimetry records. Over the period of follow-up, 131,161 person-years at risk were accrued and 21% of the subjects had die. Analysis of Standardized Mortality Ratios (SMR) showed a strong healthy worker effect (SMR all deaths 0.69, 95% confidence intervals (CI) 0.65 to 0.74; n=1,010). Exposures to uranium and external γ-radiation were not significantly associated with any cause of mortality in log-linear and linear excess relative risk models. A monotonic decreasing trend was observed for lung and lymphohematopoietic cancers across uranium exposure categories.Previous analysis of AREVA NC Pierrelatte cohort of uranium processing workers suggested that exposure to uranium may increase CSD mortality. A nested case-control study was set up to analyze dose-response relationship and adjust for major CSD risk factors (smoking, blood pressure, body mass index, total cholesterol, and glycemia) collected from medical files. The study included 102 CSD cases and 416 controls matched on attained age, gender, birth cohort, and socio-professional status. Absorbed dose was calculated taking into account the solubility of uranium compounds extracted from the JEM. CSD risk was analyzed via conditional logistic regression. A positive but imprecise association was observed (excess odds ratio per mGy 0.2, 95% CI 0.004 to 0.5). None of the considered CSD risk factor confounded this association.Compared to previous studies, our work provided important methodological improvements: consideration of specific uranium PCP, calculation of uranium organ doses, and adjustment on potential confounding factors (non-radiological exposures and CSD risk factors). The absence of association between exposure to rapidly soluble uranium compounds and mortality in the cohort of uranium enrichment workers may be indicative of the effective elimination of uranium from the human’s body. Analysis within the nested case-control study confirmed association between internal uranium exposure and CSD mortality, not confounded by CSD risk factors. Our results should be confirmed in further studies. Future work should be focused on uncertainties associated with internal uranium dose estimation, nature of association with CSD mortality, and temporal relationships between radiation and CSD risk factors

Analysis of mortality in a pooled cohort of Canadian and German uranium processing workers with no mining experience

International audiencePurpose Long-term health risks of occupational exposures to uranium processing were examined to better understand potential differences with uranium underground miners and nuclear reactor workers. Methods A cohort study of mortality of workers from Port Hope, Canada (1950–1999) and Wismut, Germany (1946–2008) employed in uranium milling, refining, and processing was conducted. Poisson regression was used to evaluate the association between cumulative exposures to radon decay products (RDP) and gamma-rays and causes of death potentially related to uranium processing. Results The pooled cohort included 7431 workers (270,201 person-years of follow-up). Mean RDP exposures were lower than in miners while gamma-ray doses were higher than in reactor workers. Both exposures were highly correlated (weighted rho = 0.81). Radiation risks of lung cancer and cardiovascular diseases (CVD) in males were increased but not statistically significant and compatible with risks estimated for miners and reactor workers, respectively. Higher RDP-associated CVD risks were observed for exposures 5–14 years prior to diagnosis compared to later exposures and among those employed <5 years. Radiation risks of solid cancers excluding lung cancer were increased, but not statistically significant, both for males and females, while all other causes of death were not associated with exposures. Conclusions In the largest study of uranium processing workers to systematically examine radiation risks of multiple outcomes from RDP exposures and gamma-rays, estimated radiation risks were compatible with risks reported for uranium miners and nuclear reactor workers. Continued follow-up and pooling with other cohorts of uranium processing workers are necessary for future comparisons with other workers of the nuclear fuel cycle. © 2017, The Author(s)

Cancer and non-cancer mortality among French uranium cycle workers: the TRACY cohort

Objectives: The health effects of internal contamination by radionuclides, and notably by uranium, are poorly characterised. New cohorts of uranium workers are needed to better examine these effects. This paper analyses for the first time the mortality profile of the French cohort of uranium cycle workers. It considers mortality from cancer and non-cancer causes. Methods: The cohort includes workers employed at least 6 months between 1958 and 2006 in French companies involved in the production of nuclear fuel. Vital status and causes of death were collected from French national registries. Workers were followed-up from 1 January 1968 to 31 December 2008. Standardised mortality ratios (SMRs) were computed based on mortality rates for the French general population. Results: The cohort includes 12 649 workers (88% men). The average length of follow-up is 27 years and the mean age at the end of the study is 60 years. Large mortality deficits are observed for non-cancer causes of death such as non-cancer respiratory diseases (SMR=0.51 (0.41 to 0.63)) and circulatory diseases (SMR=0.68 (0.62 to 0.74)). A mortality deficit of lower magnitude is also observed for all cancers combined (SMR (95% CI): 0.76 (0.71 to 0.81)). Pleural mesothelioma is elevated (SMR=2.04 (1.19 to 3.27)). Conclusions: A healthy worker effect is observed in this new cohort of workers involved in the uranium cycle. Collection of individual information on internal uranium exposure as well as other risk factors is underway, to allow for the investigation of uranium related risks

Cancer and non-cancer mortality among French uranium cycle workers: the TRACY cohort

Objectives: The health effects of internal contamination by radionuclides, and notably by uranium, are poorly characterised. New cohorts of uranium workers are needed to better examine these effects. This paper analyses for the first time the mortality profile of the French cohort of uranium cycle workers. It considers mortality from cancer and non-cancer causes. Methods: The cohort includes workers employed at least 6 months between 1958 and 2006 in French companies involved in the production of nuclear fuel. Vital status and causes of death were collected from French national registries. Workers were followed-up from 1 January 1968 to 31 December 2008. Standardised mortality ratios (SMRs) were computed based on mortality rates for the French general population. Results: The cohort includes 12 649 workers (88% men). The average length of follow-up is 27 years and the mean age at the end of the study is 60 years. Large mortality deficits are observed for non-cancer causes of death such as non-cancer respiratory diseases (SMR=0.51 (0.41 to 0.63)) and circulatory diseases (SMR=0.68 (0.62 to 0.74)). A mortality deficit of lower magnitude is also observed for all cancers combined (SMR (95% CI): 0.76 (0.71 to 0.81)). Pleural mesothelioma is elevated (SMR=2.04 (1.19 to 3.27)). Conclusions: A healthy worker effect is observed in this new cohort of workers involved in the uranium cycle. Collection of individual information on internal uranium exposure as well as other risk factors is underway, to allow for the investigation of uranium related risks

Mortality (1968-2008) in a French cohort of uranium enrichment workers potentially exposed to rapidly soluble uranium compounds

International audienceObjectives Until recently, enrichment of uranium for civil and military purposes in France was carried out by gaseous diffusion using rapidly soluble uranium compounds. We analysed the relationship between exposure to soluble uranium compounds and exposure to external γ-radiation and mortality in a cohort of 4688 French uranium enrichment workers who were employed between 1964 and 2006. Methods Data on individual annual exposure to radiological and non-radiological hazards were collected for workers of the AREVA NC, CEA and Eurodif uranium enrichment plants from job-exposure matrixes and external dosimetry records, differentiating between natural, enriched and depleted uranium. Cause-specific mortality was compared with the French general population via standardised mortality ratios (SMR), and was analysed via Poisson regression using log-linear and linear excess relative risk models. Results Over the period of follow-up, 131 161 personyears at risk were accrued and 21% of the subjects had died. A strong healthy worker effect was observed all causes SMR=0.69, 95% CI 0.65 to 0.74. SMR for pleural cancer was significantly increased (2.3, 95% CI 1.06 to 4.4), but was only based on nine cases. Internal uranium and external γ-radiation exposures were not significantly associated with any cause of mortality. Conclusions This is the first study of French uranium enrichment workers. Although limited in statistical power, further follow-up of this cohort, estimation of internal uranium doses and pooling with similar cohorts should elucidate potential risks associated with exposure to soluble uranium compounds