W O N EXPOSURE AND LUNG CANCER RISK by :

As information on indoor air quality accumulated* it became apparent that radon and its progeny are invariably present in indoor environments and that concentrations may reach unacceptably high levels. The lung cancer excess anong miners exposed to radon progeny raised concern that exposure to radon progeny might also cause lung cancer in the general population. This presentation first provides an ovemiew of radon daughter carcinogenesis, and then reviews the recent BEIR IV report. The report described a statistical model* based on analysis of data from four studies of miners, for estimating the lung cancer risk associated with exposure to radon progeny. Tbe analyses showed that the risk of radon exposure declines with time since exposure and with increasing age. The BEIR IV committee concluded that radon progeny and cigarette smoking interact in a multiplicative fashion and that exposure-dose relationships are similar for exposure in homes and in mines. Radon decays with a half-life of 3.82 days into a series of solid, short-lived radioisotopes that are collectively referred to as radon daughters or radon progeny. Two of these isotopes, polonium-218 and polonium-214* emit alpha particles* high energy and high mass particles consisting of two protons and two neutrons. When these emissions take place within the lung as inhaled radon progeny decay* the genetic material of the cells lining the airways may be damaged and lung cancer may result. The mining of radioactive ores that release radon was the first occupation associated with an increased risk of lung cancer. Over 100 years ago* Harting and Hesse described autopsy findings in eastern European miners that documented an occupational lung cancer hazard. Excess lung cancer occurrence has subsequently been found in uranium miners in the United States, Czechoslovakia, France] and Canada; and in other underground miners exposed to radon progeny including Newfoundland fluorspar miners, Swedish and U.S. metal miners, British and French iron miners, and Chinese and British tin miners (1). Exposure of animals to radon and its progeny has confirmed that radon progeny cause lung cancer and the association between lung cancer in miners and radon exposure is generally accepted as causal