Objective Linear and non-linear dose–response relationships between radiation absorbed dose to the lung from internally deposited uranium and external sources and circulatory system disease (CSD) mortality were examined in a cohort of 23 731 male and 5552 female US uranium enrichment workers.
Methods Rate ratios (RRs) for categories of lung dose and linear excess relative rates (ERRs) per unit lung dose were estimated to evaluate the associations between lung absorbed dose and death from ischaemic heart disease (IHD) and cerebrovascular disease.
Results There was a suggestion of modestly increased IHD risk in workers with internal uranium lung dose above 1 milligray (mGy) (RR=1.4, 95% CI 0.76 to 2.3) and a statistically significantly increased IHD risk with external dose exceeding 150 mGy (RR=1.3, 95% CI 1.1 to 1.6) compared with the lowest exposed groups. ERRs per milligray were positive for IHD and uranium internal dose and for both outcomes per gray external dose, although the CIs generally included the null.
Conclusions Non-linear dose–response models using restricted cubic splines revealed sublinear responses at lower internal doses, suggesting that linear models that are common in radioepidemiological cancer studies may poorly describe the association between uranium internal dose and CSD mortality.
- mortality studies
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Contributors JLA designed the study. JLA and RDD estimated the exposure. JLA, JY and SJB developed the analytical strategy. SJB conducted the statistical analyses. JLA had the lead role in writing the manuscript, and RDD, SJB, JY and KK-R participated in writing the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Disclaimer The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was approved by the Institutional Review Board (IRB) of the National Institute for Occupational Safety and Health (NIOSH).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. Data are protected by a 308(d) assurance of confidentiality that stipulates the data can only be accessed through a National Center for Health Statistics (NCHS) Research Data Center (RDC). Data will be made available to an NCHS RDC upon approval of a reasonable proposal for the data.
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