Assessment of the risk of developing lung cancer from indoor radon exposure as a function of smoking-induced morphometric changes

Abstract Lung cancer now accounts for about one-quarter of all malignancies in developed countries and is the leading cause of cancer-related death. More than 80% of these deaths are caused by smoking. The second most important factor in causing this serious disease is radon and its decay products. Without an understanding of their synergistic effect on lung cancer, it is not possible to properly assess the radon risk to the general population, including groups of smokers with different smoking habits. The goal of this study was to investigate the interaction mechanism between these two carcinogens and to propose a microdosimetric model that can predict the increase in lung cancer incidence resulting from indoor radon exposure combined with smoking at levels typical for residential areas. Our calculations suggest that the bronchial dose for a specific group of smokers (“healthy smokers”) may be lower than that for nonsmokers. By contrast, smokers with chronic lung obstruction may receive up to 100% more radiation dose. The critical threshold of cumulative smoking exposure that distinguishes “healthy” smokers from those with chronic lung obstruction was found to be around 20 pack-years. These findings align well with epidemiological and clinical observations.