If inhaled, radon decay products that have attached to the surface of aerosols, dusts, and smoke particles, become deeply lodged or trapped in the lungs, where they can radiate and penetrate the cells of mucous membranes, bronchi, and other pulmonary tissues. The ionizing radiation energy affecting the bronchial epithelial cells is believed to initiate the process of carcinogenesis (cancer).
Although radon-related lung cancers are mainly seen in the upper airways, radon increases the incidence of all histological types of lung cancer, including small cell carcinoma, aden carcinoma, and squamous cell carcinoma. Lung cancer due to inhalation of radon decay products constitutes the only known risk associated with radon. In studies done, variables such as age, duration of exposure, time since initiation of exposure and especially the use of tobacco have been found to influence individual risk. In fact, the use of tobacco multiplies the risk of radon-induced lung cancer enormously.
The radon health risk is underscored by the fact that in 1988 Congress added Title III on Indoor Radon Abatement to the Toxic Substances Control Act. It codified and funded EPA’s then fledgling radon program. Also that year, the Office of the U.S. Surgeon General issued a warning about radon urging all Americans to test their homes and to reduce the radon level when necessary.
Recognizing that radon is a significant public health risk, many scientific and professional organizations are able to say with certainty that thousands of preventable lung cancer deaths annually in the United States are attributable to indoor residential exposure to radon. These organizations include, but not limited to:
- American Cancer Society (http://www.cancer.org)
- American Medical Association (http://www.ama-assn.org)
- National Institute for Occupational Safety and Health (http://www.cdc.gov/NIOSH/)
- American Lung Association (http://www.lungusa.org/)
- National Cancer Institute (http://www.cancer.gov/)
- National Medical Association (http://www.nmanet.org/)
- Vanderbilt-Ingram Cancer Center (http://www.vicc.org/)
- Memorial Sloan-Kettering Cancer Center (http://www.mskcc.org)
These and other research organizations have collected enough data to prove with certainty that thousands of preventable lung cancer deaths annually in the United States alone are attributable to indoor residential exposure to radon.