Objectives There is growing evidence of an association between low-dose external γ-radiation and circulatory system diseases (CSDs), yet sparse data exist about an association with chronic internal uranium exposure and the role of non-radiation risk factors. We conducted a nested case–control study of French AREVA NC Pierrelatte nuclear workers employed between 1960 and 2005 to estimate CSD risks adjusting for major CSD risk factors (smoking, blood pressure, body mass index, total cholesterol and glycaemia) and external γ-radiation dose.
Methods The study included 102 cases of death from CSD and 416 controls individually matched on age, gender, birth cohort and socio-professional status. Information on CSD risk factors was collected from occupational medical records. Organ-specific absorbed doses were estimated using biomonitoring data, taking into account exposure regime and uranium physicochemical properties. External γ-radiation was measured by individual dosimeter badges. Analysis was conducted with conditional logistic regression.
Results Workers were exposed to very low radiation doses (mean γ-radiation dose 2 and lung uranium dose 1 mGy). A positive but imprecise association was observed (excess OR per mGy 0.2, 95% CI 0.004 to 0.5). Results obtained after adjustment suggest that uranium exposure might be an independent CSD risk factor.
Conclusions Our results suggest that a positive association might exist between internal uranium exposure and CSD mortality, not confounded by CSD risk factors. Future work should focus on numerous uncertainties associated with internal uranium dose estimation and on understanding biological pathway of CSD after protracted low-dose internal radiation exposure.
- circulatory disease
- nested case-control study
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Contributors IGC, JPG, DL and SZ designed the study. ED, EB and SZ estimated exposure. DL, IGC, LBZ and SZ participated in developing the study analytical strategy. CN and ES helped in the acquisition of biomonitoring data. SZ conducted statistical analyses and had the lead role in writing the manuscript.
Funding This research was performed in the frame of EU project CURE and was supported by grants from the ‘Health, Environment, and Toxicology’ scientific programme of the Région Île-de-France, the European Commission-funded network of excellence DoReMi and the École des Hautes Études en Santé Publique. The contents of the study are solely the responsibility of the authors and do not necessarily represent the official views of the funding agencies.
Competing interests CN was employed by AREVA and had no control over the study design or statistical analysis.
Ethics approval The study has been approved by the French Data Protection Authority (CNIL) (declaration no. DR-2012-611).
Provenance and peer review Not commissioned; externally peer reviewed.