Radon and lung cancer: the BEIR IV Report.

The National Academy of Sciences' BEIR IV Report (1988) deals primarily with lung cancer risks in human populations exposed to internally deposited alpha-emitting Rn and its decay products. Quantitative risk estimates for lung cancer are derived from analyses of epidemiologic data. A modified excess relative risk model of lung cancer mortality of worker exposure to Rn progeny in underground miners is developed. This models the excess risk per WLM (working level month) in terms of time intervals prior to an attained age, and is dependent on time since exposure and age at risk. Risk projections for the general public in indoor domestic environments are presented and cover exposure situations of current public health concern. For example, lifetime exposure to 1 WLM y-1 is estimated to increase the number of deaths due to lung cancer by a factor of about 1.5 over the current rate for both males and females in a population having the current prevalence of cigarette smoking. Occupational exposure to 4 WLM y-1 from ages 20 to 40 y is projected to increase lung cancer deaths in the general population by a factor of 1.6 over the current rate of this age cohort. In all of these cases, most of the increased risk occurs to smokers for whom the risk is up to 10 times greater than for nonsmokers. Discussion includes the extrapolation of estimates of lung cancer mortality risks from the underground miner data to the general population exposed to Rn and its decay products in the indoor domestic environment.