I read with interest the CMAJ editorial on radon, this neglected known human carcinogen.1 The majority of lung cancer deaths attributable to radon occur following relatively small exposure.2 This is explained by a nonthreshold dose– response relationship and the fact that the great majority of homes have radon concentrations lower than the cut-off point for mandatory corrective measures.
This epidemiological paradox reminds us that integrating prevention measures into building codes should be the keystone of all interventions planned with a population approach, all other interventions being oriented toward high-risk individuals, with an efficacy and an efficiency at a population scale that are debatable.3 In order to achieve any substantial impact, we would need a high radon screening rate of the highest at-risk population: smokers. In Quebec, we have estimated that 90% of radon-related deaths involve “ever-smokers.”4 Such observations have led some experts to state that “the public health problem of radon is, for the most part, a problem of radon and smoking.”5 Some experts have even recommended that smoking cessation campaigns incorporate advice regarding radon risk, screening and remediation.6
Such recommendations bring us to the frontier of a new, uncomfortable paradigm: promoting safe environments for smokers. One can legitimately question whether it is ethical to give smokers a false sense of security by intervening on radon while patients continue to smoke, however, the extraordinarily high cancer risks implied cannot be ignored. At 800 Bq/m3 (the former Canadian Guideline for residential radon), the lifetime cumulative risk of lung cancer for a smoker is one in three, 10 000 to 100 000 times higher than the levels usually tolerated by environmental regulation. This exceptional situation could justify adopting a pragmatic risk reduction perspective. Such strategies have been put forward for other public health problems (e.g., illicit drug injections). Are we ready to move in that direction for radon?
Who knows, perhaps the most effective radon screening strategies are those no one is yet willing to talk about?