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Mesothelioma Causes

Asbestos exposure is the overwhelming and only confirmed cause of mesothelioma. When an individual inhales or ingests microscopic asbestos fibers, the fibers become trapped in the lining of the lungs or other organs. The resulting cell irritation can trigger genetic mutations that cause the cells to grow and divide at abnormal rates, leading to mesothelioma.

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What Causes Mesothelioma?

Mesothelioma is caused by exposure to asbestos, a naturally-occurring mineral made up of strong, heat-resistant fibers. When these tiny asbestos fibers are disturbed and released into the air, they may be inhaled or ingested, lodging in the lining of the lungs (pleura), stomach lining (peritoneum), or other organs.

Over the course of around 20-50 years, according to the American Cancer Society (ACS), these fibers may trigger the development of mesothelioma.

While claims of other mesothelioma causes exist and some people have a higher risk of developing this rare cancer, exposure to asbestos is the only known cause of mesothelioma cancer.

Quick Facts About Mesothelioma Causes

  • According to the ACS, at least 8 out of 10 people with mesothelioma have been exposed to asbestos.
  • There is no safe minimum level of asbestos exposure.
  • According to the National Organization of Rare Diseases (NORD), asbestos is “the major associated risk factor for the development of mesothelioma.”
  • There have been cases of mesothelioma developing in individuals after even only one instance of asbestos exposure, according to NORD.

How Asbestos Exposure Causes Mesothelioma

Asbestos fibers can easily be breathed in or swallowed when released into the air. Once these tiny, nearly indestructible fibers enter the body, they may trigger a process that can lead to diseases, including mesothelioma.

Asbestos fibers are so small and strong that the body cannot expel them (through sneezing, coughing, etc.) or break them down.

Asbestos exposure causes mesothelioma through the following process:

  1. Asbestos is disturbed, often through activities like mining or the removal of asbestos insulation, releasing tiny fibers into the air.
  2. If breathed in, these tiny fibers can travel through small air passages and reach the pleura. If swallowed, the fibers may reach the peritoneum.
  3. Once inside the body, asbestos fibers can become lodged in the organ lining, inflaming and scarring the tissue.
  4. This disturbance may damage the DNA of nearby cells.
  5. Over the course of around 20-50 years, enough cell damage may cause changes that result in uncontrolled cell growth.
  6. This uncontrolled cell growth in the ling of the organs may lead to malignant (cancerous) mesothelioma.

While all types of asbestos may pose health risks, certain types may be more likely to trigger this deadly process than others.

Asbestos Types and Mesothelioma

There are different types of asbestos minerals, some of which, according to the ACS, may be more likely to cause mesothelioma.

Agencies like the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) measure the health risk of a type of asbestos based on its tendency to chip or crumble when disturbed (friability).

There are two main groups of asbestos minerals:

  • Serpentine: Serpentine fibers are long and curvy. Their shape makes it easier for the lungs to remove them, so this type of asbestos is associated with a lower mesothelioma risk.
  • Amphibole: Amphibole fibers are needle-like in shape, making them harder for the lungs to expel. This asbestos type is usually associated with mesothelioma.

Although some studies indicate that amphibole asbestos fibers pose a greater risk of causing mesothelioma, the National Cancer Institute (NCI) warns that all forms of asbestos pose health risks.

Asbestos Exposure Levels and Mesothelioma

According to the NCI, higher levels of asbestos exposure increase an individual’s health risks, including their risk of developing mesothelioma. However, the NCI warns that “the evidence suggests there is no safe level of asbestos exposure.”

While most people exposed to asbestos, even in large amounts, do not develop mesothelioma, even limited exposure can cause this deadly cancer, according to the ACS.

Where Asbestos Exposure Occurs

Asbestos exposure can happen nearly anywhere, but due to the mineral’s strength, flexibility, and insulation capabilities, asbestos was commonly used in industrial and military occupations.

Most individuals in the United States were exposed in blue-collar industries such as the construction, mining, and automotive industries. However, some individuals may also be exposed to asbestos in the home or the natural environment.

Occupational Asbestos Exposure

The most common form of asbestos exposure is occupational asbestos exposure (when a person is exposed to asbestos because of their job), according to the National Organization of Rare Diseases (NORD).

During the 1930s-1960s, the production of asbestos-containing products was at its peak in the United States, exposing many blue-collar workers to the toxic mineral.

Worksites with potential asbestos exposure risk include:

  • Mining Sites
  • Shipyards
  • Construction Sites
  • Chemical Plants
  • Oil Refineries
  • Automobile Assembly Plants
  • Coal Mines
  • Military Bases
  • Power Plants
  • Steel Mills

While asbestos use was reduced throughout the 1970s, and most uses in the United States ended after 1989, asbestos has not been completely banned or removed in certain industries.

Military Asbestos Exposure

In the United States, over 30% of people diagnosed with mesothelioma are veterans. Asbestos was used heavily in the United States military, especially in the Navy, where millions of military personnel, ship workers, and others were exposed.

The mineral’s flame-resistant and durable properties made it an excellent insulator for use in ships, vehicles, military bases, and other places.

Secondhand Asbestos Exposure

Someone may also be exposed to asbestos indirectly from another person who carried home asbestos fibers on their clothes, skin, and hair. This process is called secondhand exposure.

“There is some evidence that family members of workers heavily exposed to asbestos face an increased risk of developing mesothelioma,” according to the NCI.

Today, United States federal law requires workplaces involved with asbestos to limit the possibility of secondhand exposure, but there may still be increased risk.

Environmental Asbestos Exposure

According to the NCI, everyone experiences some level of asbestos exposure during their lifetimes because a small amount of the mineral naturally gets into the air, water, and soil.

These low levels of exposure rarely make people ill. However, there are a few places where asbestos exists in unusually high levels, putting people at increased risk for environmental asbestos exposure.

There may be naturally-occurring asbestos deposits, but more commonly, living close to asbestos mines may put people at risk of exposure.

Mesothelioma Risk Factors

According to Mayo Clinic, even when exposed to asbestos, most people never develop mesothelioma. It is not clear why certain individuals are more at risk for mesothelioma after asbestos exposure, but certain risk factors may be involved.

A risk factor is anything that affects a person’s chance of getting a disease.

Factors that may increase the risk of mesothelioma include:
  • Genetic Mutation

    According to the NCI, there is a chance that individuals with certain genetic mutations affecting cell growth may have an increased risk of mesothelioma.

  • History of Asbestos Exposure

    Individuals who were directly exposed to asbestos face an increased risk of developing mesothelioma.

  • Living With Someone Exposed to Asbestos

    Those living with someone who works around asbestos may suffer from secondhand exposure, increasing their risk of developing mesothelioma.

  • Family History of Mesothelioma

    Individuals whose parent, sibling, or child developed mesothelioma may have an increased risk of mesothelioma.

  • Radiation Therapy

    Doctors have observed that patients who were treated with radiation for cancer in the chest, on rare occasions, developed mesothelioma despite no asbestos exposure history.

While risk factors do not necessarily cause mesothelioma, individuals should know what may increase their likelihood of developing the disease so they can take extra precautions.

Can Smoking Cause Mesothelioma?

According to the NCI, individuals who smoke and suffer from asbestos exposure may have much higher health risks, specifically, lung cancer.

However, there does not appear to be a link between the combination of smoking and asbestos exposure and mesothelioma.

Other Potential Mesothelioma Causes

While asbestos exposure is the leading risk factor for the development of mesothelioma, there are mesothelioma cases in which the victim had no known history of exposure. In rare cases, researchers have linked exposure to other potential causes.

Other potential causes of mesothelioma include:

  • Erionite: Erionite is a mineral that is closely related to asbestos. According to NORD, there have been reports linking erionite exposure in Turkey to mesothelioma. The volcanic mineral is also found in the western United States.
  • Radiation therapy: According to the ACS, some studies have noticed that mesothelioma has developed in patients who were treated with radiation, which can damage cell DNA, potentially leading to cancer.
  • Viruses: Some researchers proposed a link between certain viruses such as the simian virus 40 (SV40) and mesothelioma development. However, according to NORD, most researchers no longer believe there is a link between SV40 and mesothelioma.
  • Unknown causes: In rare cases, some people develop mesothelioma that cannot be traced back to any cause.

While the disease may have other causes, asbestos exposure remains the main cause of mesothelioma.

Mesothelioma Prevention

Complete mesothelioma prevention is not possible. However, individuals can take steps to reduce their exposure to asbestos, thereby lowering their risks.

Individuals can help protect themselves and loved ones from asbestos exposure by:

  • Following safety regulations: Anyone with a chance of being exposed to asbestos during work should use all equipment and safety procedures designed for working with asbestos. Showering and changing clothes before leaving work may help protect loved ones from secondhand exposure.
  • Knowing their exposure risk: Individuals should be aware of whether or not they work with asbestos at their job. While blue-collar workers have higher risks, some commercial and public buildings still contain asbestos, which may pose a risk if the building is damaged or being renovated.
  • Taking precautions against exposure in the home: Older homes may contain asbestos, so they should be inspected for the toxic mineral to help keep individuals and their families safe. While asbestos in the home does not necessarily need to be removed, individuals should take care when remodeling, drilling, or performing other activities that may disturb asbestos fibers. Residents should never attempt to remove asbestos, themselves.
  • Speaking up about safety concerns: If someone is concerned about asbestos exposure at their workplace, they should discuss the situation with other employees, their employers, and their health and safety representatives. Workers can contact OSHA for more information on asbestos exposure or to make an inspection, if necessary.

For decades, asbestos-containing product manufacturers hid evidence of the mineral’s toxic effects from the public until eventually the truth was exposed. The decision to not inform the public caused millions of Americans to be affected by mesothelioma and other asbestos-related diseases.

While individuals can take steps to protect themselves from this devastating, incurable cancer, companies are ultimately responsible for the welfare of their workers.

Mesothelioma Support Team
Reviewed by:Dr. Mark Levin

Certified Oncologist and Hematologist

  • Fact-Checked
  • Editor

Mark Levin, MD has nearly 30 years of experience in academic and community hematology and oncology. In addition to serving as Chief or Director at four different teaching institutions throughout his life, he is also still a practicing clinician, has taught and designed formal education programs, and has authored numerous publications in various fields related to hematology and oncology.

Dr. Mark Levin is an independently paid medical reviewer.

Stephanie KiddWritten by:


Stephanie Kidd grew up in a family of civil servants, blue-collar workers, and medical caregivers. Upon graduating Summa Cum Laude from Stetson University, she began her career specializing in worker safety regulations and communications. Now, a proud member of the American Medical Writers Association (AMWA) and Editor-in-Chief of the Mesothelioma Justice Network, Stephanie serves as a voice for mesothelioma victims and their families.

View 5 Sources
  1. National Organization for Rare Disorders. (2017). Mesothelioma. Retrieved March 2, 2020, from
  2. Mayo Clinic staff. (2019). Mesothelioma. Retrieved March 2, 2020, from
  3. National Cancer Society. (2018). What Causes Malignant Mesothelioma? Retrieved March 2, 2020, from
  4. National Cancer Institute. (2017). Asbestos Exposure and Cancer Risk. Retrieved March 2, 2020, from
  5. United States Department of Labor: Occupational Safety and Health Administration. (1995). 1926.1101 App H - Substance Technical Information for Asbestos - Non-Mandatory. Retrieved March 2, 2020, from
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