Risk Factors

Asbestos affects people both directly and indirectly. People who have worked with or around asbestos are at a greater risk of developing mesothelioma, lung cancer, or asbestosis (a pneumoconiosis due to asbestos particles that is marked by thickening and scarring of lung tissue) than the general public. The risk of asbestos-related diseases increases with heavier exposure to asbestos and longer exposure time increases the risk of mesothelioma.

The risk of mesothelioma greatly increases in smokers who are exposed to asbestos.

Mesothelioma does not require constant exposure to asbestos over a long period of time. Many mesothelioma patients worked around asbestos for only a few weeks or months as a teenager doing summer jobs.

There also is an indirect risk to family members who have come in contact with asbestos dust brought home on clothing. For example, many women have developed mesothelioma because they washed their husband's clothes that had asbestos dust on them.

Not all workers exposed to asbestos develop mesothelioma or other asbestos-related diseases. It varies with the type of industry where the exposure occurred and with the extent of the exposure. If people worked with items containing asbestos that was bonded into finished products and the asbestos fibers were not released, there is no health risk. However, if these products were drilled, sawed, or the asbestos fibers were somehow released, there is a risk. When asbestos fibers are released and inhaled, the people exposed are at risk of developing an asbestos-related disease.

Some research shows a link between mesothelioma and the Simian Virus 40 (SV40), a virus found originally in monkeys. More research is needed in this area. Millions of people may have been exposed to SV40 when they received polio vaccinations between 1955 and 1963. At that time, the vaccine was developed using monkey cells. The virus was removed from the polio vaccine once it was discovered that SV40 was linked to various cancers.

Other research links mesothelioma to thorium dioxide, a radioactive substance used along with X-rays to diagnose various health conditions from the 1920s to the 1950s. Thorium dioxide, later found to cause cancer, is no longer used.

A family history of mesothelioma may increase a person's risk of developing mesothelioma, but more research is needed to understand that theory.