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Radon

Exposure to Radon Causes Lung Cancer In Non-smokers and Smokers Alike

















































Lung cancer kills thousands of Americans every year. The untimely deaths of Peter Jennings and Dana Reeve have raised public awareness about lung cancer, especially among people who have never smoked. Smoking, radon, and secondhand 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 percent of those afflicted will live beyond five years, depending upon demographic factors.  In many cases lung cancer can be prevented; this is especially true for radon.

Smoking is the leading cause of lung cancer.  Smoking causes an estimated 160,000* deaths in the U.S. every year (American Cancer Society, 2004).  And the rate among women is rising.  On January 11, 1964, Dr. Luther L. Terry, then U.S. Surgeon General, issued the first warning on the link between smoking and lung cancer.  Lung cancer now surpasses breast cancer as the number one cause of death 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 21,000 lung cancer deaths every year.  About 2,900 of these deaths occur among people who have never smoked.  On January 13, 2005, Dr. Richard H. Carmona, the U.S. Surgeon General, issued a national health advisory on radon.  Visit www.cheec.uiowa.edu/misc/radon.html for more on a study by Dr. William Field on radon-related lung cancer in women.

Secondhand smoke is the third leading cause of lung cancer and responsible for an estimated 3,000 lung cancer deaths every year.  About 1,000 of these are people that never smoked, and about 2,000 are former smokers.  Smoking affects non-smokers by exposing them to secondhand smoke.  Exposure to secondhand smoke can have serious consequences for children’s health, including asthma attacks, affecting the respiratory tract (bronchitis, pneumonia), and may cause ear infections.

Learning more about lung cancer. The following sources provide a wide range of good information about lung cancer, prevention, and treatment.

  • World Health Organization Launches Radon Effort

(June 21, 2005) The World Health Organization (WHO) says radon causes up to 15% of lung cancers worldwide.  In an effort to reduce the rate of lung cancer around the world, the World Health Organization (WHO) is launching a new international radon project to help countries increase awareness, collect data and encourage action to reduce radon-related risks. The U.S. EPA is one of several countries supporting this initiative and is encouraged by WHO’s attention to this important public health issue.  "Radon poses an easily reducible health risk to populations all over the world, but has not up to now received widespread attention," said Dr. Michael Repacholi, coordinator of WHO’s Radiation and Environmental Health Unit. He went on to say that "radon in our homes is the main source of exposure to ionizing radiation, and accounts for 50% of the public’s exposure to naturally-occurring sources of radiation in many countries." Read the WHO Press Release  Read the EPA News Release

Why is radon the public health risk that it is?

EPA estimates that about 20,000 lung cancer deaths each year in the U.S. are radon-related.  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 water.  Radon is a form of ionizing radiation and a proven carcinogen.  Lung cancer is the only known effect on human health from exposure to radon in air.  Thus far, there is no evidence that children are at greater risk of lung cancer than are adults.

Radon in air is ubiquitous. Radon is found in outdoor air and in the indoor air of buildings of all kinds.  EPA recommends homes be fixed if the radon level is 4 pCi/L (pico Curies per Liter) or more. Because there is no known safe level of exposure to radon, EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L. The average radon concentration in the indoor air of America’s homes is about 1.3 pCi/L. It is upon this level that EPA based its estimate of 20,000 radon-related lung cancers a year upon. It is for this simple reason that EPA recommends that Americans consider fixing their homes when the radon level is between 2 pCi/L and 4 pCi/L. The average concentration of radon in outdoor air is .4 pCi/L or 1/10th of EPA’s 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 population about 62 people in a 1,000 will die of lung-cancer, compared to 7.3 people in a 1,000 for never smokers. Put another way, a person who never smoked (never smoker) who is exposed to 1.3 pCi/L has a 2 in 1,000 chance of lung cancer; while a smoker has a 20 in 1,000 chance of dying from lung cancer. Figure A compares the risks between smokers and never smokers; smokers are at a much higher risk than never smokers, e.g., at 8 pCi/L the risk to smokers is six times the risk to never smokers.

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 Americans to test their homes and to reduce the radon level when necessary (U.S. Surgeon General).

Unfortunately, many Americans presume that because the action level is 4 pCi/L, a radon level of less than 4 pCi/L is ‘safe’. This perception is altogether 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 in their homes; especially in rooms that are below grade (e.g., basements), rooms that are in contact with the ground and those rooms immediately above them.

It's never too late to reduce your risk of lung cancer.   Don't wait to test and fix a radon problem.   If you are a smoker, stop smoking.  Consider quitting.  Until you can quit, smoke outside and provide your family with a smoke-free home (www.epa.gov/smokefree).

Take the Smoke-free Home Pledge today!

Definitions

Radon

Radon is a gaseous radioactive element having the symbol Rn, the atomic number 86, an atomic weight of 222, a melting point of -71ºC, a boiling point of -62ºC, and (depending on the source, there are between 20 and 25 isotopes of radon - 20 cited in the chemical summary, 25 listed in the table of isotopes); it is an extremely toxic, colorless gas; it can be condensed to a transparent liquid and to an opaque, glowing solid; it is derived from the radioactive decay of radium and is used in cancer treatment, as a tracer in leak detection, and in radiography. (From the word radium, the substance from which it is derived.)  Sources: Condensed Chemical Dictionary, and Handbook of Chemistry and Physics, 69th ed., CRC Press, Boca Raton, FL, 1988.

EPA's Integrated Risk Information System profile on Radon 222 [CASRN 14859-67-7] is located at: epa.gov/iris/subst/0275.htm

Sources of Radon

Earth and rock beneath home; well water; building materials.

What are the Health Effects From Exposure to Radon

No immediate symptoms. Based on an updated Assessment of Risk for Radon in Homes, radon in indoor air is estimated to cause about 21,000 lung cancer deaths each year in the United States. Smokers are at higher risk of developing Radon-induced lung cancer. Lung cancer is the only health effect which has been definitively linked with radon exposure. Lung cancer would usually occur years (5-25) after exposure. There is no evidence that other respiratory diseases, such as asthma, are caused by radon exposure and there is no evidence that children are at any greater risk of radon induced lung cancer than adults.

What is  the Average Level of Radon Found in a Home?

Based on a national residential radon survey completed in 1991, the average indoor radon level is about 1.3 picocuries per liter (pCi/L) in the United States. The average outdoor level is about 0.4 pCi/L.

What's the Debate on Radon?

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 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.

How do we know radon is a carcinogen?

The World Health Organization (WHO), the National Academy of Sciences, the US Department of Health and Human Services, as well as EPA, have classified radon as a known human carcinogen, because of the wealth of biological and epidemiological evidence and data showing the connection between exposure to radon and lung cancer in humans.

There have been many studies conducted by many different organizations in many nations around the world to examine the relationship of radon exposure and human lung cancer. The largest and most recent of these was an international study, led by the National Cancer Institute (NCI), which examined the data on 68,000 underground miners who were exposed to a wide range of radon levels. The studies of miners are very useful because the subjects are humans, not rats, as in many cancer research studies. These miners are dying of lung cancer at 5 times the rate expected for the general population. Over many years scientists around the world have conducted exhaustive research to verify the cause-effect relationship between radon exposure and the observed increased lung cancer deaths in these miners and to eliminate other possible causes.

In addition, there is an overlap between radon exposures received by miners who got lung cancer and the exposures people would receive over their lifetime in a home at EPA's action level of 4 pCi/L, i.e., the lung cancer risk in miners has been documented at exposure levels comparable to those which occur in homes/residences.

How many cases does it take to make residential radon epidemiology studies meaningful?

To have a reasonable certainty in the conclusions, many thousands of cases are required to detect the increased risk of lung cancer due to radon. This is because the more things that cause a disease the harder it is to separate one cause from another, thus it takes many cases to pinpoint the risk from each separate cause. The U.S. Public Health Service radon experts estimate that 10,000 to 30,000 cases, and twice as many controls would be needed to conduct a definitive epidemiologic study of residential radon lung cancer risk. The residential studies conducted to date have all included between 50 and 1500 cases and thus have been too small to provide conclusive information.

Some years ago this same process was used to detect an increased risk of lung cancer due to cigarette smoking. It took many years of study to make the positive link between the cause and effect of smoking and lung cancer. Most of the increased lung cancer risk is attributable to smoking through mathematical modeling. The research process for smoking was very laborious. However, radon's process is even more challenging because radon's contribution to increased lung cancer risk (12%) is difficult to see against the large background of lung cancer due to other causes, which include smoking, asbestos, some heavy metals and other types of radiation; i.e., detecting radon-related lung cancer is like trying to detect a 12% increase of sand on a beach already full of sand.

Finally, it is difficult to accurately determine radon exposures in residential settings since we are estimating past exposures from current measurements. The number of required study participants increases with the difficulty in determining the exposure.

Why are residential epidemiology studies of radon so complicated?

There are many factors that must be considered when designing a residential radon epidemiology study. It is very expensive and often impossible to design a study that takes all the pertinent factors into consideration. These factors include:

  • Mobility: people move a lot over their lifetime; it is virtually impossible to go back and test every home where an individual has lived;
  • Housing Stock Changes: over time, older homes are often destroyed or remodeled, thus radon measurements will be non-existent or highly varied; a home's radon level may change, higher or lower, over time if new ventilation systems are installed, the occupancy patterns are substantially different, or the home's foundation shifts or cracks appear.
  • Inaccurate Histories: often a majority of the lung cancer cases (individuals) being studied are deceased or too sick to be interviewed by researchers. This requires reliance on second-hand information which may not be as accurate. These inaccuracies primarily affect:
  • Residence History: a child or other relative may not be aware of all residences occupied by the patient - particularly if the occupancy is distant in time or of relatively short duration. Even if the surrogate respondent is aware of a residence they may not have enough additional information to allow researchers to locate the home.
  • Smoking History: smoking history historically has reliability problems. Individuals may under-estimate the amount they smoke. Conversely, relatives or friends may over-estimate smoking histor.

Other: complicating factors other than variations in smoking habits include an individual's: genetics, lifestyle, exposure to other carcinogens, and home heating, venting and air conditioning preferences.

Are there any residential epidemiology studies finding increased risk of lung cancer due to radon?

Yes, several residential epidemiology studies have found an increased risk of lung cancer due to residential exposures (i.e. Sweden, New Jersey ) These studies are also just pieces of a much bigger puzzle that is being put together.  The National Academy of Sciences' BEIR VI Report examines in detail the available studies of radon and lung cancer in homes, as well as the studies of underground miners.

Why can we be sure about radon's health risk?

We already have a wealth of scientific data on the relationship between radon exposure and the development of lung cancer. The scientific experts agree that the occupational miner data is a very solid base from which to estimate risk of lung cancer deaths annually. While residential radon epidemiology studies will improve what we know about radon, they will not supersede the occupational data.  Health authorities like the Centers for Disease Control (CDC), the Surgeon General , the American Lung Association, the American Medical Association, and others agree that we know enough now to recommend radon testing and to encourage public action when levels are above 4 pCi/L. The most comprehensive of these efforts has been the National Academy of Science's Biological Effects of Ionizing Radiation (BEIR VI) Report.  This report reinforces that radon is the second-leading cause of lung cancer and is a serious public health problem.  As in the case of cigarette smoking, it would probably take many years and rigorous scientific research to produce the composite data needed to make an even more definitive conclusion.

What did the National Academy of Sciences (NAS) published a report on radon and lung cancer say?

The NAS published its latest analysis of health research on radon, the Biological Effects of Ionizing Radiation (BEIR VI) Report in 1999. This is the most comprehensive review effort to date. The Committee was charged with:

  • reviewing all current miner and residential data, as well as all existing cellular-biological data,
  • comparing the dose per unit exposure effects of radon in mines and homes, and examining:
  • interactions between radon exposure and smoking, and
  • any exposure-rate effect (alteration of effect by intensity of exposure).

How can you find a qualified radon service professional in your area?

If you are interested in finding a qualified radon service professional to test or mitigate your home, or you need to purchase a radon measurement device, you should:

Contact your State Radon Contact to determine what are, or whether there are, requirements associated with providing radon measurement and or radon mitigation's/reductions in your State. Some States maintain lists of contractors available in their state or they have proficiency programs or requirements of their own.

Contact one or both of the two privately-run Radon Proficiency Program (listed here alphabetically) who are offering proficiency listing/accreditation/certification in radon testing and mitigation.
Radon Potential Map
Zone 1  Highest Potential (greater than 4 pCi/L)
Zone 2  Moderate Potential (from 2 to 4 pCi/L)
Zone 3  Low Potential (less than 2 pCi/L)
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