Cohort profile: four early uranium processing facilities in the US and Canada

Purpose Pooling of individual-level data for workers involved in uranium refining and processing (excluding enrichment) may provide valuable insights into risks from occupational uranium and external ionizing radiation exposures. Methods Data were pooled for workers from four uranium processing facilities (Fernald, Mallinckrodt and Middlesex from the U.S.; and Port Hope, Canada). Employment began as early as the 1930s and follow-up was as late as 2017. Workers were exposed to high concentrations of uranium, radium, and their decay products, as well as gamma radiation and ambient radon decay products. Exposure and outcome data were harmonized using similar definitions and dose reconstruction methods. Standardized mortality ratios (SMR) were estimated. Results In total, 560 deaths from lung cancer, 503 non-malignant respiratory diseases, 67 renal diseases, 1,596 ischemic heart diseases, and 101 dementia and Alzheimer's disease (AD) were detected in the pooled cohort of over 12,400 workers (similar to 1,300 females). Mean cumulative doses were 45 millisievert for whole-body external ionizing radiation exposure and 172 milligray for lung dose from radon decay products. Only SMR for dementia and AD among males was statistically significant (SMR=1.29; 95% confidence interval: 1.04, 1.54). Conclusions This is the largest study to date to examine long-term health risks of uranium processing workers.

Automated summary

Pooling individual-level data from uranium processing workers revealed increased risks of various diseases such as lung cancer, respiratory diseases, renal diseases, ischemic heart diseases, and dementia and Alzheimer's disease due to long-term exposure to uranium and external ionizing radiation. This study represents the largest investigation to date on the long-term health risks of uranium processing workers.