Eric Samson

External radiation exposure and mortality in a cohort of French nuclear workers

Objective: To analyse the effect of external radiation exposure on the mortality of French nuclear workers. Methods: A cohort of 29 204 workers employed between 1950 and 1994 at the French Atomic Energy Commission (Commissariat à l’Energie Atomique (CEA)) or at the General Company of Nuclear Fuel (COmpagnie GEnérale des MAtières nucléaires (Cogema, now Areva NC)) was followed up for an average of 17.8 years. Standardised mortality ratios (SMRs) were computed with reference to French mortality rates. Dose-effect relationship were analysed through trend tests and Poisson regression, with linear and log-linear models. Results: The mean exposure to X and gamma radiation was 8.3 mSv (16.9 mSv for exposed worker population). A total of 1842 deaths occurred between 1968 and 1994. A healthy worker effect was observed, the number of deaths in the cohort being 59% of the number expected from national mortality statistics. Among the 21 main cancer sites studied, a statistically significant excess was observed only for skin melanoma, and an excess of borderline statistical significance was observed for multiple myeloma. A dose-effect relationship was observed for leukaemia after exclusion of chronic lymphoid leukaemia (CLL). The relative risk observed for non-CLL leukaemia, n = 20, was 4.1 per 100 mSv (90% CI 1.4 to 12.2), linear model and 2.2 per 100 mSv (90% CI 1.2 to 3.3), log-linear model. Significant dose-effect relationship were also observed for causes of deaths associated with alcohol consumption: mouth and pharynx cancer, cirrhosis and alcoholic psychosis and external causes of death. Conclusion: The risk of leukaemia increases with increasing exposure to external radiation; this is consistent with published results on other nuclear workers cohorts.

Characterisation of protracted low-level exposure to uranium in the workplace: A comparison of two approaches.

Retrospective estimates of internal doses received by workers in the nuclear industry following intake of radionuclides, based on bioassay data, are a benchmark method in epidemiological studies. Nonetheless, full information relative to thousands of people included in an epidemiological cohort is rarely available, thus implying difficulties to estimate exposure precisely. To evaluate the cumulative exposure to uranium in a cohort of the AREVA NC Pierrelatte plant workers, we compared the epidemiological Job Exposure Matrix (JEM) method with the dosimetric method based on biological monitoring of exposure for 30 workers randomly selected within the cohort. A moderate to strong correlation was observed between the estimators resulting from the two approaches, thereby validating the JEM as a tool that can be used to characterise cumulative exposure to uranium in the cohort. In addition, this study showed that the JEM is a valuable complement to the interpretation of bioassy, (1) in providing information on exposure periods as well as on physical and chemical form of the radionuclides and (2) in compensating for the lack of exposure data regarding the very earliest periods. Combining the two methods may improve the precision in reconstructing cumulative exposure for epidemiological studies.

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.

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.

Concerted Uranium Research in Europe (CURE): toward a collaborative project integrating dosimetry, epidemiology and radiobiology to study the effects of occupational uranium exposure.

The potential health impacts of chronic exposures to uranium, as they occur in occupational settings, are not well characterized. Most epidemiological studies have been limited by small sample sizes, and a lack of harmonization of methods used to quantify radiation doses resulting from uranium exposure. Experimental studies have shown that uranium has biological effects, but their implications for human health are not clear. New studies that would combine the strengths of large, well-designed epidemiological datasets with those of state-of-the-art biological methods would help improve the characterization of the biological and health effects of occupational uranium exposure. The aim of the European Commission concerted action CURE (Concerted Uranium Research in Europe) was to develop protocols for such a future collaborative research project, in which dosimetry, epidemiology and biology would be integrated to better characterize the effects of occupational uranium exposure. These protocols were developed from existing European cohorts of workers exposed to uranium together with expertise in epidemiology, biology and dosimetry of CURE partner institutions. The preparatory work of CURE should allow a large scale collaborative project to be launched, in order to better characterize the effects of uranium exposure and more generally of alpha particles and low doses of ionizing radiation.

Mortality Among Workers Monitored for Radiation Exposure at the French Nuclear Fuel Company

ABSTRACT A cohort of 9,285 nuclear workers employed at the French company AREVA NC specializing in the nuclear fuel cycle was established. Vital status, causes of death, employment characteristics and annual exposure to ionizing radiation were reconstructed for each individual over the time period 1977–2004. Standardized mortality ratios (SMRs) were computed using national mortality rates as an external reference. Tests for trends in mortality with duration of employment and cumulative external dose were performed. The all-cause and all-cancer mortality was significantly lower than expected from the French population. No significant excess among cancer sites studied was observed. Significant positive trends with cumulative dose were observed for colon and liver cancer and for respiratory diseases. Isolated significant trends should be carefully interpreted and considered in line with the large number of trend tests performed.

Risk of Lung Cancer Mortality in Nuclear Workers from Internal Exposure to Alpha Particle-emitting Radionuclides

Background: Carcinogenic risks of internal exposures to alpha-emitters (except radon) are poorly understood. Since exposure to alpha particles—particularly through inhalation—occurs in a range of settings, understanding consequent risks is a public health priority. We aimed to quantify dose–response relationships between lung dose from alpha-emitters and lung cancer in nuclear workers. Methods: We conducted a case–control study, nested within Belgian, French, and UK cohorts of uranium and plutonium workers. Cases were workers who died from lung cancer; one to three controls were matched to each. Lung doses from alpha-emitters were assessed using bioassay data. We estimated excess odds ratio (OR) of lung cancer per gray (Gy) of lung dose. Results: The study comprised 553 cases and 1,333 controls. Median positive total alpha lung dose was 2.42 mGy (mean: 8.13 mGy; maximum: 316 mGy); for plutonium the median was 1.27 mGy and for uranium 2.17 mGy. Excess OR/Gy (90% confidence interval)—adjusted for external radiation, socioeconomic status, and smoking—was 11 (2.6, 24) for total alpha dose, 50 (17, 106) for plutonium, and 5.3 (−1.9, 18) for uranium. Conclusions: We found strong evidence for associations between low doses from alpha-emitters and lung cancer risk. The excess OR/Gy was greater for plutonium than uranium, though confidence intervals overlap. Risk estimates were similar to those estimated previously in plutonium workers, and in uranium miners exposed to radon and its progeny. Expressed as risk/equivalent dose in sieverts (Sv), our estimates are somewhat larger than but consistent with those for atomic bomb survivors. See video abstract at, http://links.lww.com/EDE/B232.

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. Sažetak Ovo opisno presječno istraživanje ispituje usklađenost radnika s opremom u pogledu mnogobrojnih rizika u industriji nuklearnoga goriva. Inventar opreme izradio je stručnjak iz područja higijene rada, zadužen za zaštitnu opremu pri francuskoj tvornici za obogaćivanje urana EURODIF. Upitnik o svome odnosu prema zaštitnoj opremi ispunilo je 227 (10 %) nasumično odabranih zaposlenih i umirovljenih radnika te tvornice. Podaci o izloženosti iz matrice profesionalne izloženosti u tvornici EURODIF upotrijebljeni su kako bi se utvrdilo ovisi li korištenje opreme o stupnju izloženosti. U istraživanju se izlaže model korištenja zaštitne opreme, koji ovisi o rizicima i dostupnoj opremi. Oprema za zaštitu od urana i rukavice među najbolje su ocijenjenima, a zaštitne naočale među najgorima. Ustanovili smo da, za većinu rizika za koje je poznato da mogu uzrokovati rak ili trajnu zdravstvenu štetu, povremena i sustavna uporaba opreme ovisi o stupnju izloženosti (test homogenosti, p<0,05; test trenda, p<0,05). Među radnicima je nužno poticati kontinuiranu uporabu opreme dugoročnim unaprjeđenjima sustava upravljanja i učinkovitom komunikacijom njihove uprave i nadzornika. Za kreiranje preciznog modela pojedinačne izloženosti nužno je razmotriti korištenje i učinkovitost osobne zaštitne opreme.

Half-century archives of occupational medical data on French nuclear workers: a dusty warehouse or gold mine for epidemiological research?

Abstract This article discusses the availability and completeness of medical data on workers from the AREVA NC Pierrelatte nuclear plant and their possible use in epidemiological research on cardiovascular and metabolic disorders related to internal exposure to uranium. We created a computer database from files on 394 eligible workers included in an ongoing nested case-control study from a larger cohort of 2897 French nuclear workers. For each worker, we collected records of previous employment, job positions, job descriptions, medical visits, and blood test results from medical history. The dataset counts 9,471 medical examinations and 12,735 blood test results. For almost all of the parameters relevant for research on cardiovascular risk, data completeness and availability is over 90 %, but it varies with time and improves in the latest time period. In the absence of biobanks, collecting and computerising available good-quality occupational medicine archive data constitutes a valuable alternative for epidemiological and aetiological research in occupational health. Biobanks rarely contain biological samples over an entire worker’s carrier and medical data from nuclear industry archives might make up for unavailable biomarkers that could provide information on cardiovascular and metabolic diseases Sažetak U ovome se članku raspravlja o dostupnosti i potpunosti medicinskih podataka o radnicima iz nuklearne elektrane AREVA NC Pierrelatte te o njihovoj korisnosti za epidemiološka ispitivanja krvožilnih i metaboličkih poremećaja povezanih s izloženosti uranu. Na temelju zdravstvenih kartona 394 radnika koji su dio većeg kohortnog ispitivanja s 2897 radnika u francuskim nuklearnim elektranama stvorena je elektronička baza podataka s informacijama o ranijem zaposlenju, položaju, opisu posla, liječničkim pregledima i krvnim nalazima. Baza obuhvaća podatke iz 9.471 liječničkog pregleda te 12.735 krvnih nalaza. Dostupnost i potpunost podataka za gotovo sve parametre važne za procjenu rizika od bolesti srca i krvožilja bile su više od 90 %, ali neujednačene, i popravljale su se tek prema kraju 50-godišnjeg praćenja. U nedostatku biobanaka, prikupljanje i digitalizacija pouzdanih arhivskih podataka iz medicine rada vrijedan su alternativni izvor za epidemiološka i etiološka ispitivanja. Biobanke rijetko čuvaju biološke uzorke radnika cijeli njegov radni vijek, pa zdravstveni podaci čuvani u arhivima nuklearnih elektrana mogu kvalitetno dopuniti prazninu uslijed nedostatka biomarkera i dati uvid u nastanak i razvoj bolesti metabolizma te srca i krvožilja

Estimating historic exposures at the European Gaseous Diffusion plants

This paper describes the methods and results of an occupational exposure assessment covering 30 years of operation of the EURODIF establishment (1978-2008). The exposure assessment includes radiological, physical and chemical hazards, and takes into account of organizational changes at the establishment. Furthermore, it includes efforts to better quantify the levels of exposures using available industrial hygiene and health physics data. In total, 227 workers participated in the assessment of 26 different occupational exposures in 102 general workstations through 1978-2008. Only 7% of exposure levels were rectified by experts for internal consistency reasons. Noise, heat, trichloroethylene and soluble uranium compounds were the most prevalent exposures at the plant although their levels tended to decrease across time. Assessments of occupational exposure to noise based on JEM exposure levels were fairly well correlated with noise measurement data (Spearmans correlation coefficient, ρ=0.43) while JEM-based assessments of uranium exposure were not well correlated with uranium atmospheric measurements. This study demonstrates the importance of non-radiological exposure in the nuclear fuel industry and highlights the difficulties in managing the risks arising from these exposures. Occupational exposures remain difficult to quantify due to the scarcity of reliable monitoring data and the absence of binding occupational exposure limits for some of considered hazards.