Does Asbestos Always Lead to Mesothelioma?

No, not everyone exposed to asbestos is diagnosed with mesothelioma. Even for those exposed to large amounts of asbestos, mesothelioma is rare.

Does Asbestos Always Lead to Mesothelioma?

No, not everyone exposed to asbestos is diagnosed with mesothelioma. Even for those exposed to large amounts of asbestos, mesothelioma is rare. Although asbestos is the primary cause of mesothelioma, there are a number of risk factors that make certain people more likely to develop this cancer. When asbestos fibers are inhaled or ingested, they cause scarring and inflammation, which can develop into a mesothelioma tumor.

Research has shown that 80% of all cases of mesothelioma are caused by known exposure to asbestos. There are no other proven causes of mesothelioma. Researchers continue to investigate other possible causes and risk factors, such as exposure to the SV40 virus or minerals that look like asbestos. Mesothelioma was practically unknown until the 20th century.

Mesothelioma incidence rates increased as industries expanded the use of asbestos. The only proven cause of mesothelioma is exposure to asbestos. Most risk factors for mesothelioma involve different sources of exposure to this mineral. Other risk factors, such as the genes you inherit or exposure to the simian virus 40, known as SV40, have not been shown to cause mesothelioma.

Other potential risk factors that remain unproven causes of mesothelioma include genetic factors and exposure to radiation, zeolite minerals, and the polio vaccine between 1955 and 1963 that was contaminated with simian virus 40 (SV40).Asbestos fibers take an average of 20 to 50 years to convert normal mesothelial cells into mesothelioma cancer cells. This time lag between exposure and the development of the disease is known as the latency period. Asbestos fibers take decades to cause damage that leads to mesothelioma, but once mesothelial cells become cancerous, they can quickly form mesothelioma tumors that grow and spread within months to a few years.According to the American Cancer Society, 80% of mesothelioma cases are caused by known exposure to asbestos. Studies have shown that radiation treatment for other types of cancer or certain genetic markers may increase the risk of developing mesothelioma.

However, asbestos is still the only proven cause of the disease.The risk of developing mesothelioma is closely related to the amount of asbestos a person is exposed to and the duration of exposure. People exposed at a young age, for a long time, and at higher levels are more likely to develop this cancer. Even so, most people exposed to asbestos, even in large numbers, do not get mesothelioma. Other factors, such as a person's genes or having had radiation therapy in the past, may make them more likely to develop mesothelioma when exposed to asbestos.Exposure to asbestos is the leading cause of pleural mesothelioma.

About 8 out of 10 people with mesothelioma have been exposed to asbestos. When asbestos fibers are inhaled, they travel to the ends of the small airways and reach the pleura, where they can cause inflammation and scarring. This can damage the cells' DNA and cause changes that cause uncontrolled cell growth.If ingested, these fibers can reach the abdominal lining, where they may play a role in causing peritoneal mesothelioma. However, most people exposed to asbestos, even in large numbers, do not get mesothelioma.

Being exposed to large amounts of asbestos for a long period of time increases the risk of mesothelioma. Many people with mesothelioma in the abdomen (peritoneal mesothelioma) have also been exposed to asbestos. Between 70 and 80% of people diagnosed with mesothelioma have been exposed to asbestos. Asbestos is a group of natural minerals found on earth.

Because of its strong, flexible fibers and fire retardant properties, asbestos was once commonly added to cement, insulation, roof tiles and other products. People who are involved in the manufacture of products containing asbestos or who install or maintain these products may inhale or swallow asbestos fibers. These fibers can also be carried in asbestos dust on clothing or personal items, exposing workers' family members to potentially high levels of minerals. Current safety regulations require people working with asbestos to wear protective equipment and to shower and change clothes before leaving the work site.

On its own, smoking does not increase the risk of mesothelioma, but the combination of smoking and exposure to asbestos may increase the risk of certain types of lung cancer. Demolition workers, drywall removers, asbestos removal workers, firefighters, and automobile workers may also be exposed to asbestos fibers. Amphibulous asbestos has straight needle-like fibers that are more fragile than those of serpentine asbestos and have a more limited manufacturing capacity (1). There are six types of fibrous asbestos silicates (actinolite, asbestos grunerite, anthophyllite, chrysotile, crocidolite and tremolite), all of which are capable of causing mesothelioma; however, only three types have been used commercially.

Malignant mesothelioma (MM) rates have been shown to increase proportionallyto cumulative exposure to asbestos and increase with the third to fourth power of time since first exposure to asbestos when based on observations of 20-40 years latency period. Other work has suggested that increased risk observed during first 20-30 years after first exposure may flatten more than 40 years after first exposure. There is some evidence that familiesof people exposed to asbestos are at increased risk for developing mesothelioma. Mesothelioma has also been reported in people without occupational exposure who live near mines (1).

In addition EPA's page provides links for information about health effects including suggestions for homeowners who suspect presence in their homes and laws/regulations applicable. Those who work with products must follow safety procedures, protect themselves from secondary exposure among family members they live with. Most people diagnosed with mesothelioma were exposed while working with products containing this mineral.

Jeannie Kotzur
Jeannie Kotzur

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