Mesothelioma & Asbestos
Asbestos was widely used in the manufacturing and building
industries for most of the second half of the 20th century for
its fireproofing and heat resistant properties. It was
not associated with causing mesothelioma until 1960. In
1960 it was shown that occupational expsoure to asbestos led
to a greatly increased risk of mesothelioma.
The two types of asbestos that cause mesothelioma are
serpentines or the corkscrew curly asbestos fibers and the
amphiboles or the rod-like fibers. Since these fibers are
insoluble, it is thought that the body reaction to them is the
trigger to mesothelioma.
Asbestos was banned in 1986 in the United States and banned
in 1999 for the United Kingdom. There has been a recent
increase in diagnosis of mesothelioma cases. This is in
small part due to a better awareness of the disease but
unfortunately more due to the fact that it generally takes 20
years before patients first show signs of
mesothelioma. It is expected that cases will
continue to increase until 2020 which will be 20 years after
the United Kingdom banned asbestos. Even though the U.S.
and U.K. both have banned it, people are still widely exposed
to asbestos mostly in older buildings.
For more information about the link between asbestos and
mesothelioma, you may want to review the scientific article by
Christopher Wagner about a mining area using asbestos in South
Africa (1960). This is one of the most commonly
Here is some formal research done on this topic.
Chrysotile asbestos is the main cause of pleural mesothelioma.
Smith AH, Wright CC., School of Public Health, University of California, Berkeley 94720, USA.
In contrast to amphibole forms of asbestos, chrysotile asbestos is often claimed to be a minor cause of malignant pleural mesothelioma, a fatal cancer of the thoracic cavity. This article examines the evidence from studies that relates to this issue. Examination of studies makes it clear that chrysotile asbestos is similar in potency to amphibole asbestos. Since asbestos is the major cause of mesothelioma, and chrysotile constitutes 95% of all asbestos use world wide, it can be concluded that chrysotile asbestos is the main cause of pleural mesothelioma in humans.
Malignant mesothelioma: attributable risk of asbestos exposure
R Spirtas, EF Heineman, L Bernstein, GW Beebe, RJ Keehn, A Stark, BL Harlow and J Benichou
Epidemiology and Biostatistics Program, National Cancer Institute, Bethesda, MD.
Evaluating a study of malignant mesothelioma through patterns of exposure to asbestos. Cases, identified from medical files and death certificates from 41 different sources. 208 studied were definite or probable mesothelioma with a control group of 533 cases had died of other causes. Direct exposure to asbestos was determined from responses to questions. Indirect exposures were assessed through residential histories and reported contact to asbestos. Among men with pleural mesothelioma the attributable risk for exposure to asbestos was 88%. For men, the AR of peritoneal cancer was 58%. For women combined, the AR was 23%. Most of the pleural and peritoneal mesotheliomas in the men studied were attributable to exposure to asbestos. The situation in women was less definitive.
Pleural mesothelioma in Sweden: an analysis according to the use of asbestos
B Jarvholm, A Englund and M Albin
Department of Occupational and Environmental Medicine, Umea University, Sweden.
To investigate if preventive measures taken to reduce the occupational exposure to asbestos have resulted in a decreased incidence of pleural mesothelioma in Sweden. The cases of pleural mesothelioma were identified through the Swedish Cancer Register. In 1995, around 80 cases of pleural mesothelioma could be attributed to exposure to asbestos. The incidence was considerably higher in the men born between 1935 and 1944 than in men born earlier. The annual incidence of pleural mesothelioma attributable to occupational exposure to asbestos is today larger than all fatal occupational accidents in Sweden. There is no obvious indication that the preventive measures have decreased the risk of pleural mesothelioma.
The pathogenesis of mesothelioma.
Carbone M, Kratzke RA, Testa JR.
Cancer Immunology Program, Cardinal Bernardin Cancer Center, Department of Pathology, Loyola University Chicago, USA.
About 80% of malignant mesotheliomas in the Western World develop in individuals with higher than background exposure to asbestos. Only a fraction of those exposed to asbestos develop mesothelioma, indicating that additional factors play a role. Simian virus 40 a DNA tumor virus that preferentially causes mesothelioma in hamsters, has been detected in several human mesotheliomas... SV40 might contribute to tumor development... Asbestos appears to increase SV40-mediated transformation of human mesothelial cells in vitro, suggesting that asbestos and SV40 may be cocarcinogens.
Non-asbestos-related malignant mesothelioma
Peterson JT Jr, Greenberg SD, Buffler PA.
The existing medical literature concerning non-asbestos-related malignant mesotheliomas was reviewed for evidence of other agents associated with the induction of malignant mesothelioma. In most reviews of malignant mesothelioma, there are a significant proportion of cases without documented asbestos exposure . Furthermore, there are well-documented agents other than asbestos that induce malignant mesothelioma in animals, and strong evidence exists that such is the case in man.