Mesothelioma is a cancer of the tissue (mesothelium) that lines your lungs, stomach, and other primary organs. Mesothelioma is rare. Doctors diagnose approximately 3,000 people each year in the United States. There are a number of cancer risk factors for mesothelioma.
Highest risk of mesothelioma
Exposure to asbestos is the highest risk factor for contracting mesothelioma. When asbestos breaks up, people may inhale or swallow the tiny dust particles that appear. This can subsequently cause mesothelioma cancer. There is evidence of working with asbestos in approximately 70 to 90 percent of mesothelioma cancer cases.1 There are a number of factors that can determine the risk of contracting mesothelioma in this way:
- How much asbestos the individual is exposed to2
- How long the individual is exposed
- The size, shape, and chemical construction of the asbestos fibers
- Tthe source of the exposure
- Individual risk factors, such as any medical history
Research suggests that amphibole forms of asbestos may be more harmful than chrysotile.3 This is because amphibole asbestos particles stay in the lungs longer.
How individuals are exposed to asbestos
Asbestos was used extensively in all branches of the military for many years, especially during World War II and the Korean conflict. During World War II, 4.3 million Americans4 worked in shipyards. Many of these people were exposed to asbestos. Asbestos was also once commonly used in the heating and construction industry. It was particularly common in the manufacture and fitting of flooring, roof shingles, and insulation. Workers in asbestos mines and mills are at a high risk of contracting mesothelioma. This is due to the high level of asbestos particles in the air.
Smoking and mesothelioma
Smoking does not cause mesothelioma cancer.5 The combination of smoking and exposure to asbestos, however, can lead to asbestosis. This will significantly increase the risk of lung cancer. Smoking will not increase the risk of mesothelioma. But it will increase the risk of lung cancer by 50 percent.
Other risk factors
Direct exposure to asbestos is not the only risk factor. Other risk factors6 for mesothelioma include:
- Secondhand exposure to asbestos at work by inhaling asbestos dust from the clothes of others workers
- Living with somebody who works with asbestos, as these workers will bring the particles home on their clothes and body
- Exposure to the simian virus 40 (or SV40), which doctors used in the polio vaccine between 1955 and 1963
- X-ray tests using a substance called thorium dioxide7 (or thorotrast)
- Contact with zeolite, a mineral found naturally in the Anatolia region of Turkey, which has similar properties to asbestos
Ongoing studies into risk factors for mesothelioma
Scientists continue to research the risk of contracting mesothelioma. Researchers believe that there may be a risk of mesothelioma cancer from exposure to carbon nanotubes.8 There is no conclusive evidence for this as yet.