RADON, CIGARETTE-SMOKE, AND LUNG-CANCER - A REANALYSIS OF THE COLORADO PLATEAU URANIUM MINERS DATA

Much of our knowledge regarding the interaction of radon and tobacco s moke in the etiology of human lung cancer derives from studies of uran ium miners. In this article, we present a re-analysis of lung cancer m ortality in the Colorado Plateau miners' cohort within the framework o f the two-mutation clonal expansion model of carcinogenesis. This anal ysis takes into account the patterns of exposure to radon and cigarett e smoke experienced by individuals in the cohort. A simultaneous re-an alysis of the British doctors' cohort indicated that those model param eters relating to the effects of tobacco were comparable in the two da ta sets. We found no evidence of interaction between radon and tobacco smoke with respect to their joint effect on the first or second stage mutation rates or on the rate of proliferation of initiated cells. Th e age-specific relative risks associated with joint exposure to radon and cigarette smoke, however, were supra-additive but submultiplicativ e. The analysis also confirmed that fractionation of radon exposures l eads to higher lung cancer risks. Finally, we present some estimates o f lung cancer risk from environmental radon exposure for nonsmokers an d smokers.