Aug. 9, 2008
By Mayo Clinic Staff
Asbestos exposure: The primary risk factor for mesothelioma
Asbestos is a mineral that's found naturally in the environment. Asbestos fibers are strong and resistant to heat, making them useful in a wide variety of applications, such as in insulation, cement, brakes, shingles, flooring and many other products. People who work around asbestos fibers are thought to have the greatest risk of mesothelioma.
When asbestos is broken up, such as during the mining process or when removing asbestos insulation, dust may be created. If the dust is inhaled or swallowed, the asbestos fibers may settle in the lungs or in the stomach, where they can cause irritation that may lead to mesothelioma, though how exactly this happens isn't understood.
Mesothelioma risk is believed to be increased in people who are exposed to high levels of asbestos, in people who are exposed to asbestos over a long period of time and in people exposed to asbestos at a young age. It can take 30 to 40 years or more for mesothelioma to develop as a result of asbestos exposure.
Some people with years of asbestos exposure never develop mesothelioma. And yet, others with very brief exposure develop the disease. This indicates that other factors may be involved in determining whether someone gets mesothelioma or doesn't. For instance, you could inherit a predisposition to cancer or some other condition could increase your risk.
Possible risk factors
Factors that may increase the risk of mesothelioma include:
Personal history of asbestos exposure. If you've been directly exposed to asbestos fibers at work or at home, your risk of mesothelioma is greatly increased.
Living with someone who works with asbestos. People who are exposed to asbestos may carry the fibers home on their skin and clothing. These stray fibers can put others in the home at risk of mesothelioma. People who work with asbestos should shower and change clothes before leaving work.
Smoking. Risk of mesothelioma is increased greatly in smokers who are exposed to asbestos.
SV40. Some research indicates a link between mesothelioma and simian virus 40 (SV40), a virus originally found in monkeys. Millions of people may have been exposed to SV40 when receiving polio vaccinations between 1955 and 1963, because the vaccine was developed using monkey cells. Once it was discovered that SV40 was linked to certain cancers, the virus was removed from the polio vaccine. Whether SV40 increases the risk of mesothelioma is a point of debate, and more research is needed.
Radiation. Some research links mesothelioma to the radioactive substance thorium dioxide, which was used along with X-rays to diagnose various health conditions from the 1920s to the 1950s. Thorium dioxide was later found to cause cancer and is no longer used.
Family history. A family history of mesothelioma may increase your risk of mesothelioma, but more research is needed to understand this theory.
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