Mesothelioma Causes

Expert Fact Checked

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James Stevenson, M.D. Thoracic Medical Oncologist

Asbestos exposure causes mesothelioma. Exposure happens when people inhale or ingest asbestos. The fibers can then settle into some organ linings, causing inflammation. Over time, this inflammation can cause cancer. The risk of mesothelioma may increase with age and radiation exposure.

01. What Causes Mesothelioma?

What Is the Cause of Mesothelioma?

The only confirmed cause of mesothelioma is asbestos exposure. Asbestos is a mineral consisting of microscopic fibers. Individuals may inhale or ingest the fibers when they become airborne. Asbestos fibers that then settle in certain areas of the body can eventually lead to mesothelioma.

Any amount of asbestos exposure is considered dangerous and may cause mesothelioma or other asbestos-related diseases.

For decades, manufacturers used the mineral in thousands of products, exposing workers and the general public to asbestos. The World Health Organization estimates asbestos causes about half of all occupational cancer deaths.

How Does Asbestos Cause Mesothelioma?

Experts do not know exactly how asbestos causes mesothelioma.

A graphic showing how asbestos causes mesothelioma. An individual inhales asbestos fibers, which enter the lungs. The fibers settle in the lining around the lungs, causing inflammation and damage. This can eventually lead to mesothelioma.

They suggest the following events may lead to the cancer:

  • Exposure: An individual inhales or ingests asbestos fibers.
  • Embedding: The fibers embed in thin tissue linings made of mesothelial cells – for example, the lining around the lungs (pleura).
  • Inflammation: The fibers cause inflammation where they settle.
  • Cell damage: Over time, inflammation leads to damage and cancerous changes in the mesothelial cells.
  • Cancer: As a result, these changes cause mesothelioma to develop.

It can be a long time between initial asbestos exposure and when symptoms of mesothelioma become apparent. Mesothelioma has a latency period of 10 – 50 years.

Breaking It Down: How Asbestos Damages DNA and Promotes Cancer

Cancer can develop from damage to a person’s DNA. Harmful substances, like asbestos, can cause direct and indirect damage to the DNA. For instance, asbestos interferes with cell division. This in turn can damage DNA. The damage to DNA can allow the development of mesothelioma.

As explained in the process above, asbestos fibers also cause inflammation of tissues. Inflammatory substances can damage DNA. These substances may also be involved in scarring of the lungs. All of these changes can lead to DNA damage and, ultimately, malignant mesothelioma.

02. How Do You Get Mesothelioma?

How Do You Get Mesothelioma?

People may develop mesothelioma after exposure to asbestos. While any amount of exposure is dangerous, those who experience regular exposure are more likely to develop mesothelioma. Exposure often happens at work, but it can also occur at home and in old buildings like schools.

People may also face exposure more indirectly. For instance, interactions with an asbestos worker wearing contaminated clothing can cause secondary exposure.

Occupational Asbestos Exposure

People are most commonly exposed to asbestos at work. They may have worked directly with the mineral, such as handling or mining raw asbestos. Others may work in facilities that used or manufactured asbestos products. Certain occupations have an increased risk of long-term exposure, including construction workers and veterans.

For decades, asbestos companies manufactured thousands of products with the mineral. By 1980, regulations restricted the use of asbestos. But workers continue to risk occupational asbestos exposure from older structures and products.

Asbestos Exposure Outside of the Workplace

Asbestos exposure can also occur outside of the workplace. According to the National Cancer Institute, most people are exposed to some level of asbestos in their lives. Low-level or one-time exposures present a smaller risk of developing asbestos-related illnesses than long-term exposures.

But the general public faces ongoing exposure risks from legacy asbestos use. For instance, homes and buildings constructed before 1980 may still contain asbestos construction products.

In general, asbestos materials that are intact and undisturbed do not pose immediate exposure risks. However, activities like do-it-yourself (DIY) remodeling projects may damage asbestos materials. This can cause fibers to become airborne, leading to exposure risks. As such, it’s best to always leave the handling of any potential asbestos materials to professionals.

In recent years, testing has found asbestos in various modern consumer products, too. For instance, talcum powder products like makeup have been contaminated with asbestos.

Secondary Asbestos Exposure

Secondary exposure happens when someone unknowingly transports asbestos on their person. For instance, fibers may settle on asbestos workers’ clothing. Anyone who comes into contact with these clothes may inhale or ingest the fibers.

For example, Heather Von St. James developed pleural mesothelioma from secondary exposure. As a child, she came into frequent contact with her father’s asbestos-coated work jacket.

People who suspect any type of asbestos exposure can speak with their doctors. Together, they can come up with a plan to monitor for potential symptoms.

03. Mesothelioma Risk Factors

Mesothelioma Risk Factors

Asbestos exposure is the only confirmed cause of mesothelioma. Data indicates more than 80% of mesothelioma cases occur in people with a confirmed history of asbestos exposure. Other factors may also increase an individual’s risk of developing mesothelioma after exposure.

Difference Between Cause and Risk Factor

  • Cause: This is something that directly leads to development of a disease.
  • Risk factor: This does not lead to a disease but may increase the chances of developing one.

Risk factors for mesothelioma include:

  • Advanced age
  • Alcohol consumption*
  • Gender
  • Germline BAP1 mutations
  • Poor overall health
  • Radiation exposure
  • Simian virus 40 (SV40)
  • Tobacco use*
  • Zeolite/erionite exposure

*These are general risk factors for cancer

Increased Mesothelioma Risk Among the Elderly

One common misconception about mesothelioma is it only develops in the elderly. More than two-thirds of pleural mesothelioma diagnoses occur in people 65 years or older. It’s rare in people under age 45. But sometimes mesothelioma is diagnosed in younger patients, too.

The Centers for Disease Control and Prevention reports the following data from 1999 to 2020:

  • Approximately 5,697 mesothelioma diagnoses occurred in patients younger than 55.
  • Approximately 64,113 mesothelioma diagnoses occurred in patients 55 and older.

Mesothelioma’s long latency period may contribute to elevated risk among older individuals.

Greater Mesothelioma Incidence Among Men

Mesothelioma is not gender-specific but does occur most often among men. Data indicates pleural mesothelioma is diagnosed at least twice as often in men than women.

This difference may be because more men work in asbestos industries. Historically, many asbestos occupations, like mining and working in shipyards, have more male employees than female.

Health and Lifestyle Risk Factors

Several health and lifestyle factors may increase a person’s risk of developing cancer, including:

  • Alcohol consumption: Research suggests someone who regularly drinks alcohol has an increased risk of cancer. The more a person drinks, the higher the risk.
  • Eating certain foods: Research suggests some foods may elevate the risk of cancer. These include cooked, starchy foods — like French fries — and meats cooked at high temperatures.
  • Lack of physical activity: Data suggests higher levels of physical activity may decrease the risk of some cancers. This may mean that sedentary lifestyles increase the risk of cancer.
  • Obesity: Research suggests obesity may carry a greater risk of cancer. But this risk may result from other factors related to obesity. For example, underlying conditions may be causing obesity. Those conditions, not obesity, may increase the risk of cancer.

Any of these may increase the risk of developing mesothelioma or other cancers after asbestos exposure. Other lifestyle choices, like smoking tobacco, may affect cancer risk too.

Can Smoking Cause Mesothelioma?

Research has not proven a definitive link between smoking and mesothelioma. But people who smoke and have been exposed to asbestos may have a higher risk of developing diseases like asbestos lung cancer. Smokers also may have been exposed to asbestos from their cigarettes. In the 1950s, Kent Micronite cigarette filters contained asbestos.

Other Mesothelioma Risk Factors

Asbestos exposure can cause mesothelioma tumors to develop. The risk factors above may increase the likelihood of developing mesothelioma. Some research shows there are other potential mesothelioma risk factors, too. These include the SV40 viral infection, exposure to radiation or erionite and BAP1 and other gene mutations.

Germline BAP1 Gene Mutations

  • The BAP1 gene suppresses tumors. A mutation of the gene has been linked to increased risk of cancers, including mesothelioma.
  • Some research links a BAP1 mutation to the development of mesothelioma at an earlier age.
  • Mesothelioma patients with this mutation may have better life expectancy than patients without it.

Simian Virus 40 (SV40)

  • The simian virus 40 (SV40) has been linked to mesothelioma in a few cases.
  • Some data indicates SV40 infections may increase a person’s risk of developing mesothelioma.
  • Some testing has found evidence of previous SV40 infection in pleural mesothelioma patients.

Radiation Exposure

  • Radiation exposure may increase the risk of developing mesothelioma.
  • Radiation exposure may occur with certain cancer treatments, X-rays or atomic energy work.


  • Erionite is part of a mineral group called zeolites. It is often found in volcanic ash.
  • Some geographic areas with high levels of erionite also have high rates of mesothelioma.

Asbestos exposure is the only confirmed cause of mesothelioma. If exposed, any of these risk factors may increase the chances of developing this disease. Regardless of risk factors, patients can speak to their doctors about suspected or known asbestos exposure. Doctors can help asbestos-exposed individuals watch for potential symptoms of related conditions.

04. Lowering Risks

Can You Lower the Risk of Mesothelioma?

Avoiding asbestos exposure is the best way to lower the risk of mesothelioma. Taking the following steps may help reduce a person’s risk of asbestos exposure:

  • Build awareness of past asbestos uses: Although there are some ways to help identify asbestos-containing materials, humans cannot see individual fibers without a microscope. Avoiding interaction with products that could contain asbestos may help avoid exposure.
  • Follow all asbestos job safety guidelines: For people working at asbestos jobsites, this includes wearing personal protective equipment and following decontamination practices.
  • Hire asbestos professionals to test and safely handle any asbestos products: Buildings, including homes and schools, constructed before the 1980s may contain asbestos materials. Before starting any renovation projects, old buildings should be inspected for asbestos.

The government has also implemented various asbestos regulations to help manage exposure risks. For instance, the Occupational Safety and Health Administration has regulations to help protect workers from asbestos exposure.

But the United States still lacks a full asbestos ban. Legacy uses of asbestos still remain in many old buildings, jobsites and homes. The Environmental Protection Agency (EPA) has been working on an investigation of asbestos and other toxins, which could result in a full ban. In 2024, the EPA announced a rule banning “ongoing uses” of chrysotile asbestos, one of the six asbestos types.

For any individuals who suspect previous asbestos exposure, it’s important to consult their healthcare team. Doctors may help watch for symptoms of asbestos-related diseases.

05. Common Questions

Common Questions About Mesothelioma Causes

What causes mesothelioma other than asbestos?

Asbestos exposure is the only confirmed cause of mesothelioma. Radiation exposure, certain genetic conditions, erionite and other factors may increase an individual’s risk of developing mesothelioma after exposure.

Who is at risk for mesothelioma?

People who experience frequent, long-term asbestos exposure are most at risk for developing mesothelioma. In general, regular exposure to asbestos is most common at asbestos jobsites. Certain occupations like construction workers, shipyard workers and veterans face a higher risk of exposure.

How much asbestos exposure causes mesothelioma?

No amount of asbestos exposure is considered safe. Regular, long-term exposure to asbestos puts individuals at a higher risk of developing mesothelioma. But even one-time or short-term exposure may cause mesothelioma and other asbestos illnesses.