Health Effects of Radon

  • How can radon affect people's health?

Almost all risk from radon comes from breathing air with radon and its decay products. Radon decay products cause lung cancer. The health risk of ingesting radon, in water for example, is dwarfed by the risk of inhaling radon and its decay products. They occur in indoor air or with tobacco smoke. Alpha radiation directly causes damage to sensitive lung tissue. Most of the radiation dose is not actually from radon itself, though, which is mostly exhaled. It comes from radon's chain of short-lived solid decay products that are inhaled and lodge in the airways of the lungs. These radionuclides decay quickly, producing other radionuclides that continue damaging the lung tissue.

There is no safe level of radon--any exposure poses some risk of cancer. In two 1999 reports, the National Academy of Sciences (NAS) concluded after an exhaustive review that radon in indoor air is the second leading cause of lung cancer in the U.S. after cigarette smoking. The NAS estimated that 15,000-22,000 Americans die every year from radon-related lung cancer. Cigarette smoke makes radon much more dangerous. When people who smoke are exposed to radon as well, the risk of developing lung cancer is significantly higher than the risk of smoking alone. People who don't smoke, but are exposed to second hand smoke, also have higher risk of lung cancer from radon indoors.

The NAS also estimated that radon in drinking water causes an additional 180 cancer deaths annually. However almost 90% of those projected deaths were from lung cancer from the inhalation of radon released to the indoor air from water, and only about 10% were from cancers of internal organs, mostly stomach cancers, from ingestion of radon in water.

  • Is there a medical test to determine exposure to radon?

Several decay products can be detected in urine, blood, and lung and bone tissue. However, these tests are not generally available through typical medical facilities. Also, they cannot be used to determine accurate exposure levels, since most radon decay products deliver their dose and decay within a few hours. Finally, these tests cannot be used to predict whether a person's exposure will cause harmful health effects, since everyone's response to exposure is different. The best way to assess exposure to radon is by measuring concentrations of radon (or radon decay products) in the air you breathe at home.

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