2020 Health Care Professionals Guide [Update] 2020 VOL 2 [Update]: September | Page 10

Retrospective occupational cohort studies of radon-exposed miners , which have been performed around the world for more than 50 years , have provided clear evidence that radon is a potent occupational carcinogen . 7 Subsequent findings from scientifically rigorous epidemiologic case-control studies performed in North America 13 , 14 and Europe 15 , 16 of individuals exposed to radon in their home have provided conclusive evidence that radon also is one of the leading environmental causes of lung cancer mortality in the general population . The evidence for radon carcinogenicity is consistent among different study types and populations . 12
Retrospective Cohort Epidemiologic Studies of Radon-Exposed Miners
Fifteen large epidemiologic cohort studies of miners have been conducted in metal , fluorspar , shale and uranium mines in the United States , Canada , Australia , China and Europe . Each of the studies reported a significantly increased risk for lung cancer with increasing radon exposure , including the studies with ranges of cumulative exposures that overlapped with the cumulative exposures occurring in the residential setting . In 1999 , the National Research Council ’ s Biological Effects of Ionizing Radiation ( BEIR ) VI Committee 7 pooled 11 of the studies that included 68,000 miners of uranium and other underground ores ( e . g ., tin , fluorspar , iron ) from various parts of the world . Each of the 11 studies reported significantly increased lung cancer mortality with increasing cumulative radon exposure , despite differences in study populations and methodologies . The pooled analysis included approximately 1.2 million person-years of follow-up and nearly 2,800 lung cancer deaths . For the population studied , the BEIR VI Committee estimated that 39 percent of lung cancer deaths among miners who smoked and 73 percent among those who never smoked were attributable to radon . 7
The findings from the pooled analysis also were utilized to estimate the risk posed by radon in the general population . The BEIR VI Committee projected that radon causes about 18,600 lung cancer deaths each year in the United States . 7 EPA updated the BEIR VI risk estimates in 2003 using more complete demographic information , concluding that out of the 157,400 lung cancer deaths in 1995 , 21,100 were attributable to protracted radon exposure . 4 Additional information on radon risk is available at www . radonleaders . org .
Case-Control Epidemiologic Radon Studies
To help assess the validity of the lung cancer risk estimates for the general population derived from the miner-based cohort studies and to directly assess the risk , more than 25 case-control epidemiologic studies have been performed since 1985 . Seven of the more scientifically rigorous case-control studies were performed in North America , 13 , 14 13 in Europe 15 , 16 and two in China . 17 Investigators from 19 of the 22 case-control studies reported increased lung cancer risk at the WHO ' s