Working with asbestos is the most common risk factor for mesothelioma. In the United States, asbestos is considered the major cause of malignant mesothelioma and has been considered "indisputably" associated with the development of mesothelioma. Indeed, the relationship between asbestos and mesothelioma is so strong that many consider mesothelioma a “signal” or “sentinel” tumor. A history of asbestos exposure exists in most cases. However, mesothelioma has been reported in some individuals without any known exposure to asbestos.
In rare cases, mesothelioma has also been associated with irradiation of the chest or abdomen, intrapleural thorium dioxide (thorotrast) as a contrast medium, and inhalation of other fibrous silicates, such as erionite or talc. Some studies suggest that simian virus 40 (SV40) may act as a cofactor in the development of mesothelioma. This has been confirmed in animal studies, but studies in humans are inconclusive. Pericardial mesothelioma may not be associated with asbestos exposure.
Incidence of mesothelioma has been found to be higher in populations living near naturally occurring asbestos. People can be exposed to naturally occurring asbestos in areas where mining or road construction is occurring, or when asbestos-containing rock is naturally weathered. Another common route of exposure is through asbestos-containing soil, which is used to whitewash, plaster, and roof houses in Greece. In central Cappadocia, Turkey, mesothelioma was causing 50% of all deaths in three small villages—Tuzköy, Karain and Sarıhıdır. Initially, this was attributed to erionite. Environmental exposure to asbestos has caused mesothelioma in places other than Turkey, including Corsica, Greece, Cyprus, China, and California.
Exposure to asbestos fibers has been recognized as an occupational health hazard since the early 20th century. Numerous epidemiological studies have associated occupational exposure to asbestos with the development of pleural plaques, diffuse pleural thickening, asbestosis, carcinoma of the lung and larynx, gastrointestinal tumors, and diffuse malignant mesothelioma of the pleura and peritoneum. Asbestos has been widely used in many industrial products, including cement, brake linings, gaskets, roof shingles, flooring products, textiles, and insulation.
Family members and others living with asbestos workers have an increased risk of developing mesothelioma, and possibly other asbestos related diseases. This risk may be the result of exposure to asbestos dust brought home on the clothing and hair of asbestos workers via washing a worker's clothes or coming into contact with asbestos-contaminated work clothing. To reduce the chance of exposing family members to asbestos fibres, asbestos workers are usually required to shower and change their clothing before leaving the workplace.
