Reassessment of radon-induced lung cancer risk with decreasing smoking prevalence in Canada

Objective: To re-assess the risk of radon-induced lung cancer with more recent and significantly reduced tobacco smoking rates in Canada. Methods: Based on the radon distribution characteristics obtained from the cross-Canada radon survey and with the EPA/BEIR VI risk model as well as the same model parameters used in previous study, Canadian population risk for radon-induced lung cancer was re-assessed with Canadian age-specific smoking prevalence data of ever smokers in 2022 and Canadian age-specific mortality rates averaged over five years from 2019 to 2022. Results: In the past 20 years from 2002 to 2022, the rates of ever-smokers among Canadians aged 15 and older dropped by 44% for males and by 42% for females. As a result, the baseline risks of lung cancer decreased by 14% for males and 10% for females. The re-evaluation indicates that 12% of lung cancer deaths among Canadian males and 13% of lung cancer deaths among Canadian females are attributable to indoor radon exposure, significantly lower than 16% of radon-induced lung cancer deaths among Canadians as estimated previously. Conclusions: This re-assessment updated the estimates of radon-induced lung cancer in Canada. The study estimated that the success of tobacco control program over time (more than 40% reduction in percentage of ever-smokers in Canadian population in the past two decades) could result in 4% less radon-induced lung cancer deaths in males and 3% less in females.