Lubin J H, Steindorf K
Epidemiologic Methods Section, National Cancer Institute, Bethesda, Maryland 20892-7368.
Radiat Res. 1995 Jan;141(1):79-85.
Residential exposure to radioactive radon and its decay products has been estimated to account for 10-12% of all lung cancer deaths in the U.S. It has been difficult to evaluate fully the impact of cigarette smoking, the most important cause of lung cancer, on this estimate, because factors for patterns of tobacco use have not been included in the risk models, since risk models are derived from studies of underground miners exposed to radon and detailed data on smoking are limited. Lung cancer risk estimates for exposure to radon progeny in smoker and non-smoker populations are obtained by applying the same risk model to each population group, thereby assuming the joint effects of smoking and exposure to radon progeny are multiplicative. However, in miners, joint relative risks (RR) for the two exposures are most consistent with an intermediate relationship between multiplicative and additive, so that the present approach likely results in an overestimate of risk in smokers and an underestimate of risk in nonsmokers. Lubin et al. (National Institutes of Health Publication No. 94-3644, 1994) present an ad hoc approach for adjusting risk models to incorporate smoking status. The approach is based on the relative magnitude of the effects of radon progeny in smokers and nonsmokers and therefore may not be applicable to non-miner populations if the proportion of smokers and the RR for smoking differ. We show that the modification can be derived explicitly by assuming an arithmetic mixture model for the joint RR for smoking and exposure to radon progeny. In this way, smoking parameters in the population of interest (the proportion of smokers and the RR of smoking) can be used directly to adjust radon progeny risk models and obtain risk estimates that are specific for smokers and nonsmokers. With an intermediate RR relationship for smoking and radon progeny, the attributable percentage of lung cancer deaths from residential radon may be twofold greater in non-smokers than in smokers.
据估计，在美国，居住环境中接触放射性氡及其衰变产物导致的肺癌死亡占所有肺癌死亡病例的10%至12%。由于风险模型源自对接触氡的地下矿工的研究，且吸烟模式因素未纳入风险模型，同时关于吸烟的详细数据有限，因此很难全面评估吸烟（肺癌最重要的病因）对这一估计的影响。通过对每个群体应用相同的风险模型来获得吸烟者和非吸烟者群体中接触氡子体的肺癌风险估计值，从而假定吸烟与接触氡子体的联合效应是相乘的。然而，在矿工中，这两种暴露的联合相对风险（RR）最符合相乘和相加之间的中间关系，因此目前的方法可能导致对吸烟者风险的高估和对非吸烟者风险的低估。卢宾等人（美国国立卫生研究院出版物第94 - 3644号，1994年）提出了一种临时方法来调整风险模型以纳入吸烟状况。该方法基于吸烟者和非吸烟者中氡子体效应的相对大小，因此如果吸烟者比例和吸烟的RR不同，可能不适用于非矿工群体。我们表明，通过假定吸烟与接触氡子体的联合RR的算术混合模型，可以明确推导这种修正。通过这种方式，目标人群中的吸烟参数（吸烟者比例和吸烟的RR）可直接用于调整氡子体风险模型，并获得针对吸烟者和非吸烟者的特定风险估计值。对于吸烟与氡子体的中间RR关系，居住性氡导致的肺癌死亡归因百分比在非吸烟者中可能比吸烟者高出两倍。
