(ENS) BRUSSELS -- Exposure to radon in homes leads to an increased risk of lung cancer, in particular among smokers, according to a new study of risk from exposure to radon gas in European homes. The first study to examine radon risk to smokers separately from risk to nonsmokers, it found that for any given level of radon, smokers have about 25 times the risk of developing lung cancer as non-smokers.
Radon can also cause lung cancer in non-smokers but the risk is low. Recent ex-smokers were also found to be at higher risk from radon than non-smokers.
The results show that radon in homes is responsible for about 20,000 lung cancer deaths in the European Union each year. This is about nine percent of the total lung cancer deaths in the EU and about two percent of cancer deaths overall.
The risk increases in proportion to the concentration of radon gas in the home and is apparent at concentrations below current remedial action levels used in most European countries.
The study, co-funded by the European Commission, combines information and analysis from 13 smaller case-control studies across Europe covering 7,148 cases of lung cancer and 14,208 controls. The cases studied come from nine European countries.
It is the largest study ever into the effects of radon exposure in European homes. Previous such studies have not been large enough to assess the risks reliably.
By comparison, in the United States, the National Academy of Sciences estimates that radon causes 19,000 cancer deaths each year. The "Annual Report on Carcinogens 2000" attributes to radon 20,000 lung cancer deaths per year.
Radon is the second leading cause of lung cancer in the United States. Among non-smokers, radon is the number one cause of U.S. lung cancer deaths.
Radon is a naturally occurring, colorless, odorless, radioactive gas found at varying levels in all houses across the European Union. It is formed from the natural decay of uranium, which is present in ordinary surface rock and in soil.
Radon that diffuses into the atmosphere usually disperses rapidly but it can accumulate indoors, especially in small buildings. Radon concentrations in houses vary widely throughout the EU and within individual countries depending on the underlying geology and the method of home construction.
The radon gas decays into radioactive solids, called radon daughters. The radon daughters attach to dust particles in the air, and can be inhaled. The inhalation of radon daughters has been linked to lung cancer.
The only way to find out if any particular home has high levels of radon is to do a test. Short-term testing devices for use from two up to 90 days, and long-term testing devices for tests from 90 days to one year are available online and from hardware stores.
High radon levels in existing houses can usually be reduced at modest cost by changes to the ventilation system, such as improving under-floor air bricks and extracting radon from beneath the building with a fan.
For new buildings, low concentrations can be achieved at low cost by installing membranes across the full footprint of the building.
The paper, "Radon in homes and risk of lung cancer," by 26 co-authors from across Europe, led by S. C. Darby of the Clinical Trials Service Unit and Epidemiological Studies Unit, Radcliffe Infirmary, Oxford, was published in the "British Medical Journal" December 21, 2004.
The European Commission issued a Recommendation (90/143/EURATOM) in 1990 on the protection of the public against indoor radon. It emphasized the need for member states to conduct surveys to identify dwellings with a potential for high radon concentrations and to provide adequate information in response to public concern.
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