Modelling lung cancer risk associated to radon exposure in the French cohort of uranium miners
A. Rogel , D. Laurier , M. Tirmarche , B Quesne
20th L.H. GRAY Conference, 17-21 Feb. 2002, Ede (NL)
The French cohort of uranium miners includes 5098 males employed as a miner since 1947, and followed up to 1994. Annual radon exposure has been reconstructed for every miner. The number of lung cancer is 125. Mean cumulative exposure is 36.5 WLM (Working Level Month: unit of exposure multiplying a concentration of radon decay products by duration of exposure), protracted over a mean duration of 11.5 years. Compared to previous studies, this cohort constitutes a population exposed to lower levels of radon during a long duration.
The dose-response relationship was modelled by linear excess relative risk models. This approach allows us to test several factors that may modify risk: period of exposure, time since exposure, attained age and dose rate.
Simple excess relative risk model shows a significant linear increase of lung cancer risk with cumulative exposure (Excess Relative Risk (ERR) = 0.9 per 100 WLM, 95% CI = [0.3 - 1.5]). The main modifier is the period of exposure: ERR after introduction of ventilation in the French mines is 10 times higher than before. A decrease in risk is also seen with time since exposure. After adjustment on these factors, no other modifying effect can be shown.
Continuation of this work is included in a European collaborative research project, aiming to a synthesis of results from epidemiology and from animal data regarding the risk associated to low levels of radon exposure. In this framework, mechanistic modelling will also be applied to this data.
This work was done in collaboration with Cogema.