Mesothelioma risk factors

Asbestos comes first

The American Cancer Society (ACS) calls asbestos exposure the main risk factor for pleural mesothelioma, the type that starts in the chest. Most pleural mesotheliomas are linked to high levels of asbestos exposure, usually at work.

Asbestos is a group of natural minerals made of tiny fibers. Because it resists heat and fire, it was used for decades in building materials, insulation, brakes, and many other products. When fibers are breathed in, ACS explains, some travel to the ends of the small airways and reach the pleura, the lining of the lung and chest wall, where they can injure cells and, over time, cause mesothelioma. Peritoneal mesothelioma, in the lining of the abdomen, may form when inhaled fibers are coughed up and swallowed.

Three points about asbestos risk matter most:

• It takes a long time. ACS says the time between first exposure and diagnosis is usually 20 to 50 years, and the risk does not go down over time after exposure stops.
• More exposure, more risk. Risk is loosely related to how much asbestos a person was exposed to and for how long. People exposed at an earlier age, for longer, and at higher levels are more likely to develop it.
• Most exposed people never get it. Even among people exposed to large amounts, most do not develop mesothelioma. Other factors, such as a person's genes, may make some people more likely to.

See asbestos exposure: jobs and places for where exposure was common, and secondhand and home exposure for exposure outside the workplace.

Who was most exposed

ACS lists some miners, factory workers, insulation manufacturers and installers, railroad and automotive workers, shipyard workers, plumbers, and construction workers among the people at higher risk. Family members can be exposed too, because workers carried fibers home on their clothes. VA adds that veterans who worked in mining, milling, shipyards, insulation, demolition of old buildings, carpentry and construction, or with flooring and roofing products may have been exposed during service.

Other risk factors

Erionite. Zeolites are minerals chemically related to asbestos. ACS notes that high mesothelioma rates in parts of Turkey are believed to be caused by erionite, a zeolite common in the rocks and soil there, and that erionite deposits have been found in several western U.S. states, including Nevada, Oregon, Utah, and Arizona.

Radiation. Some studies suggest the risk may be higher in people who had high doses of radiation to the chest or abdomen to treat another cancer. Even so, ACS notes that mesothelioma is still rare in these people.

Age. The risk rises with age. Mesothelioma can occur in young people and children, but ACS says it is rare under age 45.

Sex. Mesothelioma, especially the pleural type, is much more common in men than in women. ACS explains that this is probably because men were more likely to work in jobs with heavy asbestos exposure.

Inherited gene changes. In rare cases, mesothelioma runs in families because of a shared change (mutation) in the BAP1 gene, usually inherited from a parent. People with this change are at higher risk of mesothelioma when exposed to asbestos, and of some other cancers. If several relatives have had mesothelioma or related cancers, ask your doctor whether genetic counseling makes sense.

A factor that was studied and not confirmed

SV40 is a monkey virus. Some polio vaccines made between 1955 and 1963 were later found to be contaminated with it. Some older studies suggested a link with mesothelioma, but ACS reports that larger studies of people who received the contaminated vaccines as children have not found an increased risk.

Lowering risk today

ACS says the best way to reduce your risk is to limit asbestos exposure at home, in public buildings, and at work. If you might be exposed on the job, such as during renovation of old buildings, use all the protective equipment and safety procedures required for asbestos work. At home, materials that are intact and undisturbed generally do not pose a health risk; if they need repair or removal, EPA advises hiring a trained and accredited asbestos professional rather than doing it yourself.

Talk with your doctor

If you know or think you were exposed to asbestos, tell your doctor, even if it was decades ago. It helps them interpret symptoms such as shortness of breath, chest pain, or a lasting cough. This page explains risk factors in general; it cannot tell you your own risk.