Most of the radon gas that you inhale is also exhaled. However, some of radon’s decay products attach to dusts and aerosols in the air and are then readily deposited in the lungs. Some of these are cleared by the lung’s natural defense system, and swallowed or coughed out. Those particles that are retained for long enough release radiation, damaging surrounding lung tissues. Small amounts of radon decay products in the lung are absorbed into the blood.
Most of the radon ingested in water is excreted within hours. There is some risk from drinking water with elevated radon, because radioactive decay can occur within the body where tissues, such as the stomach lining, would be exposed. However, alpha particles emitted by radon and its decay product in water prior to drinking quickly lose their energy and are taken up by other compounds in water, and do not themselves pose a health concern.
Exposure to Radon Causes Lung Cancer in Non-Smokers and Smokers Alike
Lung cancer kills thousands of Americans every year. Smoking, radon, and second-hand smoke are the leading causes of lung cancer. Although lung cancer can be treated, the survival rate is one of the lowest for those with cancer. From the time of diagnosis, between 11 and 15% of those afflicted will live beyond five years. In many cases, lung cancer can be prevented, and this is especially true for radon.
Smoking is the leading cause of lung cancer. Smoking causes an estimated 160,000 cancer deaths in the U.S. every year, according to 2008 statistics from the American Cancer Society. And the rate among women is rising. In 1964, Dr. Luther L. Terry, then U.S. Surgeon General, issued the first warning regarding the link between smoking and lung cancer. Lung cancer now surpasses breast cancer as the number-one cause of cancer deaths among women. A smoker who is also exposed to radon has a much higher risk of lung cancer.
Radon is the number-one cause of lung cancer among non-smokers, according to EPA estimates. Overall, radon is the second-leading cause of lung cancer. Radon is responsible for about 20,000 lung cancer deaths every year. About 2,900 of these deaths occur among people who have never smoked.
Second-hand smoke is the third leading cause of lung cancer and is responsible for an estimated 3,000 lung cancer deaths every year. Smoking affects non-smokers by exposing them to second-hand smoke. Exposure to second-hand smoke can have serious consequences for children’s health, including asthma attacks. It can also affect the respiratory tract and make children vulnerable to bronchitis and pneumonia, etc. It may also lead to ear infections.
Radon is a Carcinogen
Two studies based on research conducted in North America and in Europe show definitive evidence of an association between residential radon exposure and lung cancer. Both studies combined data from several residential studies. They went a step beyond earlier findings and confirmed the radon health risks predicted by occupational studies of underground miners who breathed radon for years. Early in the debate about radon-related risks, some researchers questioned whether occupational studies could be used to calculate risks from exposure to radon in the home environment.
“These findings effectively end any doubts about the risks to Americans of having radon in their homes,” said Tom Kelly, director of EPA’s Indoor Environments Division. “We know that radon is a carcinogen. This research confirms that breathing low levels of radon can lead to lung cancer.”
Why is radon the public health risk that it is?
The EPA estimates that radon is responsible for about 20,000 lung cancer deaths each year in the United States. Exposure to radon is the second-leading cause of lung cancer after smoking. Radon is an odorless, tasteless and invisible gas produced by the decay of naturally occurring uranium in soil and groundwater. Radon is a form of ionizing radiation and a proven carcinogen. Lung cancer is the only known effect on human health from exposure to airborne radon. Thus far, there is no conclusive evidence that children are at greater risk of lung cancer than adults.
Radon in air is ubiquitous. It is found in outdoor air and in the indoor air of buildings of all kinds. The EPA recommends that the problem be addressed if a home’s radon level is 4 pCi/L (picocuries per liter) or more. Because there is no known safe level of exposure to radon, the EPA also recommends that the problem be addressed for homes with radon levels between 2 pCi/L and 4 pCi/L. The average radon concentration in the indoor air of the average American home is about 1.3 pCi/L. The EPA bases its estimate of 20,000 radon-related lung cancers a year on this number. The average concentration of radon in outdoor air is 0.4 pCi/L, or one-tenth of the EPA’s recommended 4 pCi/L action level.
For smokers, the risk of lung cancer is significant due to the synergistic effects of radon and smoking. For this at-risk population, about 62 people out of a 1,000 will die of lung cancer, compared to about seven people in 1,000 who have never smoked. Put another way, a person who has never smoked and is exposed to 1.3 pCi/L has a 2-in-1,000 chance of dying from lung cancer, while a smoker has a 20-in-1,000 chance. The risk to smokers compared to those who have never smoked is six times greater.
The radon health risk is underscored by the fact that, in 1988, the United States Congress added Title III on Indoor Radon Abatement to the Toxic Substances Control Act. It codified and funded EPA’s then-fledgling radon program. That same year, the Surgeon General issued a warning about radon, urging Americans to test their homes and to reduce the radon level, when necessary.
Unfortunately, many Americans presume that because the action level is 4 pCi/L, a radon level of less than that is considered safe. This perception is all too common in the residential real estate market. In managing any risk, we should be concerned with the greatest risk. For most Americans, their greatest exposure to radon is inside their homes, especially in rooms that are below grade (such as basements), as well as rooms that are in contact with the ground, and the rooms directly above them.
