Effect of additive interaction between tobacco smoking and domestic radon on the occurrence of lung cancer: A Spanish case-control study

Abstract

Exposure to residential radon is suspected to be a risk factor for lung cancer, in addition to tobacco smoking, the carcinogenic potential of which is firmly established by more than three decades of evidence (Lubin et al., 1994; Takkouche & Gestal-Otero, 1996). So far, few studies have focused on the effect of joint exposure to tobacco smoking and domestic radon on the occurrence of lung cancer. Such synergy or interaction has been evaluated only as the magnitude of a product term of the individual effects in a regression model in which interaction is defined as a departure from the product of the absolute effects of the two causes. This approach to synergy is uninformative if not clearly misleading. We used Rothman’s concept of interaction (Rothman, 1986), defined as a departure from additivity of the individual effects of tobacco smoking and radon, to measure this interaction.