Asbestos: Exposure to asbestos is a major risk factor for mesothelioma. The risk from long-term asbestos exposure does not decrease over time. Rather, it may take more than 20 years from the last exposure before cancer develops. Talk to a doctor if you or a loved one has a history of asbestos exposure. Today the risk of exposure for workers in the manufacturing industry is much less since asbestos, by and large, is no longer used in the United States. Although the use of asbestos has decreased dramatically since the late 1980s, asbestos may still be found in older buildings or products.
SV40: Between 1955 and 1963, some polio vaccinations were infected with SV40 (simian virus 40). There is ongoing research exploring the possibility that SV40 infections may have an effect on the development of mesothelioma. Although there is no conclusive evidence, there may be an overlap in the peak age range of those who are diagnosed with mesothelioma (ages 50 to 70) and the timing of the exposure to SV40.
Thorium dioxide: Until the 1950s, thorium dioxide (Thorotrast) was injected into the chest or abdomen before an X-ray was taken to create contrast in the image. There may be a link between the thorium dioxide, followed by a high dose of radiation, and mesothelioma.