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

OBJECTIVES: 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 person-years 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.

Attitude towards personal protective equipment in the French nuclear fuel industry.

This descriptive cross-sectional study examines the compliance of workers from the European Gaseous Diffusion Uranium Enrichment Consortium (EURODIF) with personal protection equipment (PPE) in view of the various hazards in the nuclear fuel industry. The PPE inventory was drawn up by an industrial hygienist in charge of the PPE at EURODIF. Two hundred and twenty seven (10%) randomly selected, active and retired, EURODIF workers filled in a questionnaire on their attitudes towards PPE. Exposure data from the EURODIF job exposure matrix were used to examine whether PPE usage varies according to exposure level. The study suggests a PPE usage profile that varies depending on the hazards present and PPE available. Anti-uranium PPE and gloves were among the best rated, while anti-spray goggles were the least used. We found that, for most hazards known to cause cancer or irreversible health damage, PPE usage varied according to exposure (homogeneity test, p<0.05; trend test, p<0.05). The continuous use of PPE among workers should be encouraged through improvements to the PPE management system. A precise model of individual exposure can only be designed if the use and efficiency of PPE are taken into consideration.

Does uranium induce circulatory diseases? First results from a French cohort of uranium workers.

OBJECTIVES: Increased risk of circulatory system diseases (CSDs) was observed in nuclear workers handling uranium and plutonium in Russia and the UK. This work examines the CSD mortality after chronic intake of uranium among 2897 workers (79,892 person-years) at a uranium processing plant (1960-2006) in France. METHODS: Cumulative exposure to different uranium compounds, classified by their isotopic composition and solubility type, was quantified on the basis of a plant-specific job-exposure matrix and individual job histories. HRs and associated 95% CI for CSD (n = 111) and specific CSD categories were estimated using Cox regression models, stratified on sex and birth cohort and adjusted for potential confounders. The effect of smoking was analysed among 260 smokers (42 CSD deaths). RESULTS: Compared to unexposed workers, CSD mortality was increased among workers exposed to slowly soluble reprocessed uranium (RPU) (HR = 2.13, 95% CI = 0.96 to 4.70) and natural uranium (HR = 1.73, 95% CI = 1.11 to 2.69). The risk increased with cumulative exposure and exposure duration. In the subgroup of smokers, the risk estimates were higher but with larger CIs: HR=1.91 (95% CI = 0.92 to 3.98) for natural uranium and HR = 4.78 (95% CI = 1.38 to 16.50) for RPU. CONCLUSIONS: The authors observed that exposure to slowly soluble uranium, namely RPU, may increase the risk of CSD mortality. However, these results are preliminary since the study is lacking statistical power and many other biological and lifestyle-related factors may cause CSD. More detailed investigations are necessary to confirm these findings and analyse in depth the effects of internal radiation exposure on the circulatory system.

Comparative assessing for radiological, chemical, and physical exposures at the French uranium conversion plant: Is uranium the only stressor?

This study presents the pattern of exposure to uranium and other occupational pollutants known to be potentially carcinogenic, mutagenic or toxic and used at the main uranium conversion plant in France. For different uranium compounds specified according to their solubility and purity, and 16 other categories of pollutants: chemicals, fibres, vapours, dust, and heat a time- and plant-specific job exposure matrix (JEM) was created covering the period 1960-2006. For 73 jobs and for each pollutant the amount and frequency of exposure were assessed on a four-level scale by different time periods. The JEM shows 73% sensitivity and 83% specificity. Although exposure assessment was semi-quantitative, the JEM allows computing of individual cumulative exposure score for each pollutant across time. Despite the predominant natural uranium compounds exposure, the amount of exposure to other pollutants such as TCE and other chlorinated products, asbestos, and fibres, is important at the plant. Numerous correlations detected between uranium compounds exposure and exposure to chemicals warrants improving biological monitoring of exposed workers and accounting for associated exposures in epidemiological studies. Results of this study will be used for further investigation of association between exposure and mortality among uranium conversion workers cohort.