There is no debate about radon being a lung carcinogen in humans. All major national and international organizations that have examined the health risks of radon agree that it is a lung carcinogen. The scientific community continues to conduct research to refine our understanding of the precise number of deaths attributable to radon. The National Academy of Sciences BEIR VI Report (see www.epa.gov/radon/health-risk-radon#beir) has estimated that radon causes about 15,000 to 22,000 lung cancer deaths annually based on their two-preferred models. Major scientific organizations continue to believe that approximately 12% of lung cancers annually in the United States are attributable to radon.
See radon health risks at www.epa.gov/radon/health-risk-radon