gms | German Medical Science

Introduction: Epidemiological studies of uranium miners provide key insights into the risk of lung cancer due to radon exposure. The German uranium miners study is one of the world's largest study cohorts of uranium miners. The extension of the follow-up period to 1946-2018 allows risk models to be improved.

Methods: The full cohort includes 58,972 male employees of the Wismut company in former Eastern Germany. The 1960+ sub-cohort consists of 26,764 men, who were first employed at Wismut in 1960 or later, and is characterized by low protracted radon exposure with high measurement quality. A job-exposure matrix was used to retrospectively assess the annual cumulative radon exposure of each miner in Working Level Months (WLM). Vital status and, if applicable, cause of death were followed up every five years via registration and health offices. Internal Poisson regression was used to estimate the excess relative risk (ERR) for lung cancer per cumulative radon exposure modified by attained age, time since exposure and exposure rate.

Results: The number of deaths from lung cancer amounts to 4,329 in the full cohort and 663 in the 1960+ sub-cohort. The risk of lung cancer due to radon exposure is significantly increased in both the full and the sub-cohort. Miners who had reached an age of less than 55 years, who were exposed 5 to 14 years ago and whose annual exposure rate was less than 0.5 WL are at highest risk: ERR/100 WLM = 2.50 (95% confidence interval (CI) 0.81; 4.18) for the full cohort and ERR/100 WLM = 6.92 (95% CI <0; 16.59) for the 1960+ sub-cohort. The risk of lung cancer due to radon decreases with increasing attained age and time since exposure. For the full cohort, there is an additional decrease in risk as the exposure rate increases. The risk of lung cancer due to radon is still elevated at the end of the observation period, 20 to 30 years after the mines have been closed and exposure to radon has ceased [1].

Discussion: Estimates of lung cancer risk from radon from previous analyses of the Wismut cohort were confirmed. The association between lung cancer and radon was already known to vary with age, time and exposure rate. In the 1960+ sub-cohort, a statistically significant age- and time-related effect modification of risk was found for the first time. In addition, the results of the 1960+ sub-cohort are consistent with those of a large pooled study [2].

Conclusion: The Wismut 1960+ sub-cohort provides a good basis for estimating lung cancer risks at low radon exposures and low exposure rates, which are particularly relevant for today's radiation protection. Further follow-up of this cohort will improve precision, especially at older ages and longer times since exposure.

The authors declare that they have no competing interests.

The authors declare that an ethics committee vote is not required.