Written By: Karen Selby, RN,
Last modified: September 15, 2021

What Causes Mesothelioma?

Diagram showing how asbestos develops into pleural and peritoneal mesothelioma
How Pleural and Peritoneal Mesothelioma Are Caused

Asbestos exposure is the only proven cause of mesothelioma. Most people diagnosed with the disease worked jobs that required them to handle asbestos-containing products. 

There are no other proven causes of mesothelioma. Researchers continue to investigate other potential causes and risk factors such as exposure to the SV40 virus or minerals that resemble asbestos.

Mesothelioma was virtually unknown until the 20th century. Mesothelioma incidence rates rose as industries expanded the use of asbestos.

How Do You Get Mesothelioma?

Malignant mesothelioma develops when inhaled asbestos fibers cause inflammation, scarring and cell damage. All types of asbestos cause mesothelioma, but not everyone exposed to asbestos will develop mesothelioma. 

There is a dose-response relationship between asbestos and the development of mesothelioma, which means your risk of getting the cancer increases with every exposure. However, not everyone exposed to large amounts of asbestos will develop the disease. Research shows approximately 8% to 13% of asbestos workers eventually develop mesothelioma. 

When asbestos fibers travel to different parts of the body, they can cause different types of mesothelioma. For example, when fibers get stuck in the pleura, which is the lining of the lungs, pleural mesothelioma can develop. When fibers are deposited in the peritoneum, which is the lining of the abdominal cavity, peritoneal mesothelioma can develop.

The majority of people diagnosed with mesothelioma were exposed to asbestos while working certain blue-collar jobs or serving in the military.

Occupational Asbestos Exposure

Asbestos exposure primarily happens in a workplace setting. It can also happen at home and in the natural environment, but these types of exposures are less likely to lead to mesothelioma.

Asbestos was widely used in thousands of commercial, industrial and domestic products. Examples include drywall, insulation, piping, glues and adhesives, ceiling tiles, cement and shingles.

The risk for asbestos-related illnesses is highest for people who worked with the raw mineral or with asbestos-containing products daily. Workers who manufactured or used these products were exposed to asbestos on the job. Others, including workers’ family members, faced secondary exposure at home.

High-Risk Occupations for Mesothelioma Cancer
  • Shipyard workers
  • Construction workers
  • Power plant workers
  • Chemical plant workers
  • Industrial workers
  • Insulators
  • Boiler workers
  • Auto mechanics

Construction tradesmen and firefighters can be exposed to asbestos while working in old homes and structures built with contaminated materials. Exposure can happen during a renovation, demolition or disaster response. 

Veterans also cope with higher rates of mesothelioma because the U.S. armed forces used asbestos in every branch of the military. Those who served in the Navy faced the highest risk of exposure because asbestos was used to prevent fires in shipyards and vessels. 

Secondhand Exposure to Asbestos

When the asbestos industry was booming, families of workers were also at risk. Workers often came home with asbestos fibers on their hair, work clothes, shoes and tools. This exposed family members to the toxic substance and increased their risk for mesothelioma and related diseases.

Those who worked with asbestos-contaminated talc products, such as barbers and ceramics workers, also unknowingly brought asbestos fibers home and caused mesothelioma among their children and spouses.

My father worked in steel mills for years and I remember washing his clothes, which were covered in dust.
Judy Goodson
Diagnosed with peritoneal mesothelioma in 2013

Environmental Asbestos Exposure

Because asbestos is a naturally occurring mineral, people living near large deposits in hilly or mountainous regions also face exposure. Minimal amounts of the mineral can fill the air in these regions. Still, environmental exposure is most dangerous near former asbestos mines. 

For example, in June 2009, the U.S. Environmental Protection Agency declared a public health emergency in Libby, Montana, stemming from an asbestos-contaminated vermiculite mine in the town. Thousands of town residents have been diagnosed with asbestos-related diseases, including mesothelioma.

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Primary Risk Factors for Mesothelioma

A risk factor is anything that increases the odds of developing a disease. A cause is the contributing factor that leads to a disease. For example, working in the construction industry is a risk factor, but not everyone in the industry ends up with mesothelioma. 

The only proven cause of mesothelioma is asbestos exposure. Most mesothelioma risk factors involve different sources of asbestos exposure. Other risk factors, such as genes you inherit or exposure to simian virus 40, known as SV40, have not been proven to cause mesothelioma.  

More than 125 million people throughout the world are currently at risk of exposure to asbestos in the workplace, according to the World Health Organization. About 1.3 million workers in construction and general industry remain at risk of asbestos exposure in the U.S.

Primary Risk Factors for Mesothelioma
  • Military asbestos exposure
  • Occupational asbestos exposure
  • Living with someone who worked with asbestos
  • Environmental asbestos exposure
  • DIY automotive and home renovation projects

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).

Because the combination of smoking cigarettes and exposure to asbestos greatly increases the risk of developing lung cancer, smoking often gets mistaken as a mesothelioma risk factor. Smoking on its own or in combination with asbestos exposure does not increase the risk of developing mesothelioma.

Watch: Learn how mesothelioma can develop in different parts of the body from mesothelioma specialist Dr. Marcelo DaSilva.

How Does Mesothelioma Develop?

Mesothelioma develops as a result of cell and DNA damage caused by asbestos fibers. Cells are small biological structures that make up every part of the human body. DNA is the hereditary material in our cells that is passed down from our parents and makes up our genes. DNA contains a code that tells our cells how to function properly, and asbestos fibers can damage this code.

Once asbestos is inhaled, the body has a hard time getting rid of the fibers. The fibers become lodged in tissues and accumulate with repeated exposure. After many years, these fibers may cause direct DNA damage and indirect cell damage that mutates DNA and turns normal cells into cancer cells.

It takes an average of 20 to 50 years for asbestos fibers to turn normal mesothelial cells into cancerous mesothelioma cells. This time lapse between exposure and development of disease is known as the latency period. It takes decades for asbestos fibers to cause damage that leads to mesothelioma, but once mesothelial cells turn cancerous, they can quickly form mesothelioma tumors that grow and spread within months to a few years. 

Mesothelioma starts in mesothelial cells, which make up the protective membranes of the mesothelium that cover the lungs, abdomen and heart.

Diagram showing how mesothelioma develops
Asbestos damages mesothelial cells and mutates them into cancerous mesothelioma cells.

How Is Mesothelioma Detected?

Mesothelioma is typically detected with imaging scans and officially diagnosed with a biopsy test. Blood tests also play a role, but they cannot detect mesothelioma on their own and cannot provide a diagnosis. 

A thoracoscopic biopsy is the gold standard of tests for achieving a mesothelioma diagnosis. It involves inserting a scope with a camera at the end into the chest to take a sample of suspected mesothelioma tumor tissue. The tissue sample is analyzed in a lab to confirm the presence of cancer cells.  

Doctors are working on ways to detect mesothelioma early in its development because treatment is more effective at an early stage. Researchers are developing tests that may one day detect mesothelioma early through blood or saliva samples.

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Preventing Mesothelioma

The best way to prevent mesothelioma is to follow workplace safety regulations. Protect yourself by learning more about how you might be exposed to asbestos at work and at home. 

Occupational asbestos exposure is the primary cause of mesothelioma. Those who work with asbestos products should follow safety procedures to protect themselves, and decontamination protocols to prevent secondary asbestos exposure among family members they live with. 

Be cautious of materials in old homes that may contain asbestos. Do-it-yourself renovations in older homes may put everyone in the home at risk of asbestos exposure. Test for asbestos before starting renovations and hire a professional asbestos abatement company to remove materials containing asbestos.

If you think a past job or home repair project exposed you to asbestos, you should tell your doctor and ask to be monitored for signs of asbestos-related diseases.If you or a loved one has a history of asbestos exposure — especially in the workplace — don’t wait for symptoms to arise. Instead, be proactive and talk to your doctor. Early detection offers the best opportunity for effective mesothelioma treatment.

Asbestos Removal:
While abatement is highly regulated, and fines are levied when rules are ignored, workers are still endangered when safety protocols aren’t properly followed on job sites.

Common Questions About Mesothelioma Causes

Is asbestos the only cause of mesothelioma?

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 cancers or certain genetic markers may increase the risk of developing mesothelioma. However, asbestos remains the only proven cause of the disease.

Who is at risk for mesothelioma?

Occupational asbestos exposure is the primary cause of mesothelioma. Construction workers, firefighters, industrial workers, power plant workers and shipyard workers have the greatest risk of asbestos exposure.

Wives and children of blue-collar workers are at risk of secondary asbestos exposure and mesothelioma. Men who worked with asbestos would often carry fibers home on their skin, hair, clothes and tools.

How much exposure to asbestos is harmful?

There is no safe amount of exposure to asbestos due to the size and shape of asbestos fibers. The risk of developing mesothelioma is greater with increased exposure to asbestos. Trace amounts of asbestos on clothes and skin are enough to cause mesothelioma by secondary exposure.

What should I do if I think I am developing mesothelioma?

If you are experiencing respiratory symptoms or other signs of mesothelioma and have a history of asbestos exposure, talk with your physician about being screened for the disease.

Mesothelioma doctors will order CT imaging and other tests based on your history of asbestos exposure to determine if you are developing mesothelioma.


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