Mesothelioma Causes

Expert Fact Checked

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James Stevenson, M.D. Thoracic Medical Oncologist

Asbestos exposure causes mesothelioma. Research links known asbestos exposure to 80% of all cases. Exposure often happens at work or in old buildings. After inhaling or ingesting asbestos, the fibers may settle in some organ linings. These linings can become inflamed or scarred. Cancerous cells may later develop.

01. What Causes Mesothelioma?

What Is the Cause of Mesothelioma?

Asbestos exposure is the only confirmed mesothelioma cause. Asbestos is a mineral that was used in many products and materials until the 1980s. Common sources of exposure include older buildings and workplaces in certain industries. For example, construction workers may handle materials like old asbestos insulation and drywall.

Workers in high-risk asbestos jobs face an elevated risk of exposure. This may later lead to asbestos-related diseases, like asbestosis and mesothelioma. About 8 out of 10 people with mesothelioma have experienced traceable asbestos exposure. The World Health Organization (WHO) also estimates asbestos causes about half of all occupational cancer deaths.

How Does Asbestos Cause Mesothelioma?

Asbestos exposure may cause mesothelioma to develop over the course of 10 – 50 years. Exposure can occur in two main ways: primary and secondary. People may experience primary exposure themselves in various places, like work or school.

Others may experience secondary exposure. This occurs when someone unknowingly carries asbestos fibers to a second location. This can expose other individuals in the second location to those fibers. Secondary exposure often affects family members living with asbestos workers.

Mesothelioma researchers continue studying how asbestos causes this cancer. Experts say evidence suggests the following process occurs:

  • A person ingests or inhales asbestos fibers.
  • The fibers settle in the mesothelium (thin tissue linings where mesothelial cells live).
  • The fibers cause inflammation to these thin tissues.
  • Inflammation causes damage and cancerous changes in the mesothelial cells.
  • These changes allow mesothelioma to develop.

Besides inflammation and scarring, asbestos fibers may also cause DNA damage. Damaged DNA may lead to cancers, including mesothelioma.

How Asbestos Damages DNA and Promotes Cancer

  • Asbestos interferes with cell division.
  • This interference can damage DNA.
  • Asbestos can also physically interact with DNA and change its function.
  • Asbestos causes inflammation of surrounding tissues.
  • Inflammatory substances can damage DNA.
  • Over time, DNA damage can lead to cancer.

The location of the asbestos fibers and damaged tissue and DNA affects which mesothelioma form develops. The four types of mesothelioma are:

Diagram of mesothelioma causes

02. How Do You Get Mesothelioma?

How Do You Get Mesothelioma?

Exposure to asbestos is the main cause of mesothelioma. Heavy asbestos exposure is most common for people working in at-risk occupations. But exposure may also occur in non-occupational buildings and facilities too. For example, other sources of exposure are older homes and schools.

Secondary exposure, sometimes called secondhand exposure, can also occur. For example, construction workers may come home with asbestos dust on their clothing. Other people in the household may accidentally breathe or ingest these fibers.

It is not always obvious if asbestos is present, so exposure may go unnoticed. Many industries have guidelines for recognizing and addressing asbestos. High-risk occupations for asbestos exposure can review any asbestos regulations for their profession. These regulations may help limit some exposure risks.

Occupational Asbestos Exposure

The workplace is the most common source of heavy asbestos exposure. Thousands of people have worked for asbestos companies. In the past, workers may have handled raw asbestos or asbestos-containing materials. Many facilities were constructed with asbestos materials, like asbestos cement and floor, ceiling and wall tiles.

Since the 1980s, asbestos regulations in the United States have helped restrict the use of asbestos. But these regulations are not a comprehensive ban. In many instances, asbestos still remains in older structures and products. In addition, workers still face exposure risks in industries that often used asbestos in the past.

Individuals at high risk of asbestos exposure include shipyard workers, firefighters and veterans. These individuals may encounter asbestos when working with legacy asbestos products or in older buildings, facilities, homes or schools.

Asbestos Exposure Outside of the Workplace

Asbestos exposure can also occur outside of the workplace. This includes exposure from asbestos products or old buildings like homes and schools.

The general public faces ongoing exposure risks from legacy asbestos. Legacy asbestos is still found in buildings constructed before 1980 and in various household items. Some activities disturb asbestos, which increases the risk of inhaling or ingesting it. Thus, homeowners may experience asbestos exposure when performing do-it-yourself remodeling projects. It is best to hire professionals to handle any potential asbestos materials.

Samples of some common household products have shown evidence of asbestos contamination. These products include paint, potting soils and talcum powder. Various children’s makeup products have also tested positive for asbestos.

According to the National Cancer Institute (NCI), most people are exposed to some level of asbestos at some point in their lives. This exposure may even occur from the environment. Trace amounts of asbestos can be found in the air, soil and water. However, most people do not become ill from this low-level exposure.

Secondary Asbestos Exposure

Secondary exposure happens when someone unknowingly transports asbestos on their person. For instance, the fibers may have settled on asbestos workers’ clothing, hair or skin. Anyone who comes into contact with these clothes may inhale or ingest these fibers. This most commonly affects family members.

Researchers have studied mesothelioma in family members of asbestos workers. These family members may face an increased risk of developing mesothelioma. This is due to secondary asbestos exposure.

One example is Heather Von St James. She is a mesothelioma survivor who experienced secondary asbestos exposure as a child from coming into contact with her father’s work jacket. Decades later, she developed mesothelioma. People who suspect any type of asbestos exposure can speak with their doctors. Together they can discuss risks and suggested precautions or monitoring.

03. Mesothelioma Risk Factors

Mesothelioma Risk Factors

Asbestos exposure is the only confirmed cause of mesothelioma. In fact, 80% of all mesothelioma cases occur in people with a history of known asbestos exposure. The remaining 20% of patients may be unable to pinpoint their exposure. Researchers continue studying the connection between asbestos and mesothelioma.

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.

Evidence shows various risk factors may also influence the development of mesothelioma. But risk factors do not always cause diseases to develop. There are various risk factors for mesothelioma, like age and gender.

Causes and risk factors can vary for different diseases. But some risk factors apply to many types of cancer, including mesothelioma.

Risk Factors for Mesothelioma

  • 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. But mesothelioma is diagnosed in younger patients too. It’s rare in people under age 45. The Centers for Disease Control and Prevention (CDC) reports the following data for mesothelioma diagnoses from 1999 to 2018:

  • There were 5,280 mesothelioma diagnoses in patients younger than 55.
  • There were 58,707 mesothelioma diagnoses in patients 55 and older.

Mesothelioma’s long latency period (10 – 50 years) may contribute to elevated risk among older individuals. Researchers are studying a potential genetic factor that may make its carriers more likely to develop mesothelioma at an earlier age. Some medical advances may help mesothelioma doctors diagnose the disease sooner. Earlier diagnoses may change the age-related statistics of this disease.

Greater Mesothelioma Incidence Among Men

Mesothelioma is not gender-specific but does occur most often among men. From 1999 to 2018, men accounted for almost four times the number of pleural cases than women. This difference may be because more men work in asbestos industries. Many asbestos occupations, like mining and working in shipyards, tend to have more male employees than female.

In recent years, mesothelioma diagnoses among women have been on the rise. Still, the risk of developing mesothelioma is greater among men than women.

Health and Lifestyle Risk Factors

Several health and lifestyle factors may increase a person’s risk of developing cancer and mesothelioma. Factors that may contribute to increased risk of cancer, including mesothelioma after exposure to asbestos, include:

  • 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. This includes acrylamide-containing 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. And those conditions, not obesity, may then increase the risk of cancer.
  • Other diseases or conditions: Some conditions and diseases may increase the risk that cancer will form. This includes infection with simian virus 40 (SV40).

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 the link is well established between smoking, lung disease and some forms of cancer. Asbestos exposure may also impact lung diseases. Studies show asbestos exposure combined with smoking has a higher risk of lung cancer than either factor alone.

Current evidence does not support that smoking alone increases the risk of mesothelioma. However, smoke inhalation may alter the body’s response to asbestos fibers. This might affect a person’s risk of developing mesothelioma.

Some cigarettes, like Kent Micronite, contained asbestos filters. This increased the risk of asbestos exposure in combination with general smoking risks.

Research suggests smoking impacts the lungs by:

  • Decreasing overall health: Smoking can cause many medical problems. This can affect mesothelioma development and cancer treatment side effects.
  • Increasing mucus production: Irritated air passages produce more mucus. This blocks the passage of air and affects the lungs’ self-cleaning process.
  • Weakening lung tissues: Smoking changes how lung tissues function. This allows asbestos fibers to more easily become lodged in the linings of the lungs.

Smoking may not directly cause mesothelioma, but it can have negative health effects.

Other Mesothelioma Risk Factors

Asbestos exposure causes malignant 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, BAP1 and other gene mutations and exposure to radiation or erionite.

Germline BAP1 Gene Mutations

The BAP1 gene suppresses tumors. A mutation of the gene increases the likelihood of tumor development. Some research links a BAP1 mutation to the development of mesothelioma at an earlier age. But 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 shows a link between SV40 infections and an increased risk of developing mesothelioma. Some testing also shows SV40-fighting antibodies in pleural mesothelioma patients’ blood.

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 a naturally-occurring material often found in volcanic ash. It is part of the mineral group called zeolites. Some geographic areas with high levels of erionite have high rates of mesothelioma. Though research is limited, erionite exposure may be a risk factor for developing 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. Mesothelioma Prevention

How to Prevent Mesothelioma

Avoiding asbestos exposure is the most effective way to prevent mesothelioma. In the 1980s, the Environmental Protection Agency (EPA) put asbestos regulations in place. These regulations, along with other guidelines, help protect people from asbestos. However, the lack of a full asbestos ban in the United States means exposure is still possible.

People can take care to avoid asbestos in the workplace and other high-risk areas. This includes older buildings like homes and schools. Becoming familiar with asbestos products and materials can help individuals identify potential exposure sources.

Workers in high-risk occupations for exposure should follow safety precautions while working. For example, there are many asbestos guidelines for construction workers and automotive mechanics. There are also general asbestos safety and handling regulations that workers can follow.

For homes built before the 1980s, asbestos materials may still be present. Undisturbed asbestos poses a lower risk than disturbed asbestos. Homeowners can hire professional asbestos-trained contractors for repairs, renovations and removal.

Some people may know or suspect they have experienced asbestos exposure. Others may be unaware of any exposure. Experts recommend seeking medical guidance for any possible asbestos exposure. Doctors can assess any risks and provide next steps.

Mesothelioma symptoms can take decades to present. Doctors may watch for common symptoms, like shortness of breath, weight loss and chest pain. This may help them diagnose mesothelioma sooner, which is key to earlier, and potentially more effective, treatment options. Treatment is the best way for diagnosed patients to improve their prognosis.

05. Common Questions

Common Questions About Mesothelioma Causes

What causes mesothelioma other than asbestos?

Asbestos exposure is the only confirmed cause of mesothelioma. Some risk factors may increase the chances of mesothelioma developing after asbestos exposure. These include age, gender, DNA or exposures to certain radiations and infections. Some lifestyle factors, like drinking alcohol, may also impact the development of mesothelioma.

Does asbestos exposure always cause mesothelioma?

Asbestos exposure does not always mean mesothelioma will develop. In general, mesothelioma develops in people who experienced recurring asbestos exposure at work. Many people exposed to asbestos do not go on to develop mesothelioma. But there is no safe level of asbestos exposure. Some people with brief exposure have developed asbestos diseases and cancers.

Who is at risk for mesothelioma?

People who experienced regular asbestos exposure are most at risk of developing mesothelioma. Some factors, like age and gender, may increase a person’s risk of developing mesothelioma. It can take 10 – 50 years for mesothelioma symptoms to present. This may contribute to the higher risk of mesothelioma with advanced age. Still, asbestos exposure puts people at the greatest risk of this disease.

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

Anyone at risk of asbestos exposure or mesothelioma can seek medical guidance. After discussing asbestos exposure concerns and any symptoms, doctors can provide next steps. This may include a monitoring plan or some baseline tests like CT scans. For patients with some mesothelioma symptoms, doctors may perform specific tests. Diagnosing mesothelioma early is key and working with a doctor helps support this.