Methods to derive uncertainty intervals for lifetime risks for lung cancer related to occupational radon exposure

TL;DR

This study develops methods to quantify uncertainty in lifetime lung cancer risk estimates from occupational radon exposure, emphasizing the dominant role of risk model parameter uncertainty and providing practical tools for radiation protection policy.

Contribution

It introduces and compares uncertainty interval estimation methods for lifetime risk of lung cancer due to radon, highlighting the importance of risk model parameter uncertainty and applying Bayesian and ANA techniques.

Findings

Risk model parameter uncertainty is the main contributor to total risk uncertainty.

Uncertainty intervals for lifetime risk estimates are consistent with existing literature.

Choice of lifetime risk measure has minimal impact on uncertainty intervals.

Abstract

Introduction Lifetime risks quantify health risks from radiation exposure and play an important role in radiation detriment and radon dose conversion. This study considers the lifetime risk of dying from lung cancer related to occupational radon exposure, focusing on lifetime excess absolute risk (LEAR), in addition to other lifetime risk measures. This article derives and discusses uncertainty intervals for these estimates. Methods Uncertainties in two components of lifetime risk calculations are modeled: risk model parameter estimates for excess relative risk of lung cancer and baseline mortality rates. Approximate normality assumption (ANA) methods and Bayesian techniques quantify risk model parameter uncertainty. The methods are applied to risk models from the German "Wismut" uranium miners cohort study (full cohort with follow-up 2018 and the 1960+ sub-cohort of miners hired in 1960 or later). Mortality rate uncertainty is assessed based on WHO data. Monte Carlo simulations yield uncertainty intervals, which are compared across different lifetime risk measures. Results Risk model parameter uncertainty is the largest contributor to lifetime risk uncertainty, with baseline mortality rate uncertainty also significant. For the 1960+ sub-cohort risk model, LEAR was 6.70% (95% uncertainty interval: [3.26, 12.28]) for an exposure of 2 Working Level Months from age 18-64, compared to 3.43% ([2.06, 4.84]) for the full cohort. Differences across lifetime risk measures are minor. Conclusion Here, risk model parameter uncertainty substantially drives lifetime risk uncertainty, supporting the use of ANA methods for practicality. Choice of lifetime risk measures has negligible impact. Derived uncertainty intervals align with the range of lifetime risk estimates from uranium miners studies in the literature and should inform radiation protection policies based on lifetime risks.