Exposure to asbestos is the main known risk factor for mesothelioma. People in occupations such as mining, milling, construction, plumbing, heating, insulation, carpentry, and electrical and shipyard work generally have had greater exposure to asbestos than those in other occupations and are therefore at higher risk of mesothelioma. Family members of these workers are also at higher risk than others because of indirect exposure to asbestos (in the clothes and hair of family members).
A federally mandated ban on the production and use of all asbestos products was implemented in the US in 1989. Before its dangers were known, asbestos was a common form of building insulation and was used to make a variety of products, including roofing materials and floor tiles. Because mesothelioma takes at least 20 years to develop, the widespread use of asbestos between the 1930s and the 1960s has led to the rise in mesothelioma cases since 1970.
In addition, the risk of developing mesothelioma is raised by exposure to a mineral related to asbestos, called zeolite, and to thorium dioxide (a chemical used in certain older x-rays). However, in many cases of mesothelioma, no exposure to asbestos can be documented. Another possible, and controversial, co-factor for developing mesothelioma is exposure to Simian Virus 40 (SV-40), which was found in some polio vaccines produced from 1955 to 1961.
Smoking raises the risk of lung cancer in those exposed to asbestos, but not the risk of mesothelioma.
