11 Min Read
Last Updated: 05/29/2024
Fact Checked

Written by Karen Selby, RN | Medically Reviewed By Dr. Jacques Fontaine | Edited By Walter Pacheco

What Causes Mesothelioma? 

Asbestos is the primary cause of mesothelioma. Most people diagnosed with mesothelioma were exposed to asbestos at their jobs or during military service. Asbestos-contaminated talc has also been responsible for causing mesothelioma. 

Some people also develop mesothelioma because of secondhand contact. This is sometimes called take-home exposure because workers inadvertently brought the asbestos home on clothing or gear and exposed their families. 

Mesothelioma is caused by exposure to asbestos. Patients inhale asbestos, which causes chronic inflammation that leads to genetic changes in a cell that gets changed in its DNA into a cancer cell. There’s also talc, which has been associated with the development of mesothelioma.

About 8% to 13% of people with heavy exposure to asbestos develop mesothelioma. While asbestos exposure is the main risk factor for mesothelioma, as with other cancers, family history, genetics and lifestyle may increase a person’s risk.

Researchers believe simian virus 40 is not a risk factor on its own, but the virus and asbestos may act as co-carcinogens. In some studies, researchers have found human mesothelial cells are susceptible to SV40. There are no reports of higher rates of cancer in those who received polio vaccines contaminated with SV40.

Key Facts About Mesothelioma Causes
  • Out of all people with heavy, prolonged exposure to asbestos, 8% to 13% develop mesothelioma.
  • Asbestos workers who experienced years of exposure have the highest risk of developing mesothelioma.
  • Because there is no safe amount of asbestos exposure, limited exposure can also cause mesothelioma.
  • Inhaled asbestos fibers can lodge in the membrane (mesothelium) that lines a number of cavities within the body, which can eventually cause tumors to develop.

How Does Asbestos Exposure Cause Mesothelioma?

When exposed to asbestos, people can inhale or ingest microscopic airborne fibers. Once inside the body, these asbestos fibers get trapped in the mesothelium, very thin tissue that lines certain organs. 

The fibers pierce this lining, causing inflammation and damage to the mesothelial cells. Over time, the chronic inflammation and the physical properties of asbestos fibers lead to DNA damage. Ultimately this can cause the formation of mesothelioma tumors.

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

Asbestos fibers that embed in the outer lining of the lungs can cause pleural mesothelioma. When the fibers get stuck in the abdominal cavity, they may cause peritoneal mesothelioma. 

Fibers may also embed in the pericardium surrounding the heart or the membrane that covers the testes. However, pericardial and testicular mesothelioma are both very rare.

Common Mesothelioma Risk Factors

Asbestos exposure is the biggest risk factor for a mesothelioma diagnosis. Occupational asbestos exposure ranks as the No. 1 risk factor for mesothelioma and other asbestos-related diseases, including asbestosis and pleural plaques.

The duration and intensity of asbestos exposure can affect a person’s risk of developing mesothelioma. This is called a dose-response relationship. Any amount of asbestos exposure can potentially lead to mesothelioma, however.

Mesothelioma Risk Factors
  • Asbestos exposure
  • Contaminated talc exposure
  • Family history of asbestos exposure or disease
  • High-risk jobs
  • Living near asbestos factories or deposits

Asbestos exposure is the top risk factor for mesothelioma. Other factors can further increase your chance of developing the disease. A family history of mesothelioma may raise your risk. Overall health may also potentially put some people at increased risk of developing mesothelioma from asbestos exposure.

Age is a risk factor for those with past exposure because it takes 20 to 60 years for mesothelioma to develop. However, mesothelioma can occur at any age. Rates of pleural mesothelioma are higher in men than women, but peritoneal mesothelioma affects men and women equally. 

When mesothelioma patients are unsure of the source of their asbestos exposure, I talk to them about high-risk categories, and sometimes, a light goes off. If not, we talk about other exposure examples such as a recent case of a teacher who developed mesothelioma from asbestos in the school she taught in.

How Can You Be Exposed to Asbestos?

There are several types of asbestos exposure, including occupational exposure, military exposure, secondary exposure and environmental exposure. Occupational exposure is the most common type of exposure.

While many people know if they’ve been exposed to asbestos, others may not be aware of their exposure. Understanding the different sources of exposure can help you understand your risk of developing mesothelioma. Asbestos exposure can come from unexpected places.

“In past years, most patients I spoke with knew exactly how they were exposed to asbestos,” says Dr. Snehal Smart, a Patient Advocate at The Mesothelioma Center. “Recently, however, many patients aren’t as sure initially.” 

Smart explains that, after learning more about the types of asbestos contact, some people recall  experiencing secondhand exposure from living with someone who worked around asbestos. They may also realize they had talcum powder exposure.

Occupational Exposure

The risk of developing asbestos-related diseases is highest for people who worked with the raw mineral, such as miners and workers in asbestos product manufacturing. Construction workers and firefighters today encounter asbestos while working in older buildings. Exposure can happen during renovation, demolition or disaster response.

Thousands of commercial, industrial and domestic products contained asbestos. Examples include drywall, insulation, pipes, glues, tiles, cement and talcum powder. Chrysotile asbestos was the most widely used in manufacturing, which is why it’s strongly associated with a risk of developing mesothelioma.

While products in homes contributed to asbestos contact, the greatest risk was to the people who manufactured asbestos products and those who used asbestos at work. Historically, men were more likely to have jobs with a greater risk of contact with asbestos. This has traditionally led to higher mesothelioma incidence rates in men than women.

Military Exposure

Veterans also experience higher rates of mesothelioma because of asbestos exposure. Every branch of the military used asbestos extensively on bases and in vehicles, ships and planes.

Those who served in the Navy faced the highest risk of exposure. Asbestos helped reduce fires on ships and was used in protective gear such as respirators and heat-resistant gloves for operating gun turrets.

When I was stripping asbestos insulation from below-deck steam pipes it looked like it was snowing down there.

The Honoring Our PACT Act of 2022 expanded access to health care and disability benefits for veterans exposed to toxic substances. This includes asbestos exposure, chemical exposure and contaminated water at Marine Corps Base Camp Lejeune. 

David Cutts, a pleural mesothelioma survivor, served 3 years in the Marines. His service included active duty in Vietnam in the 1960s, and he served briefly on a Navy ship where asbestos was prevalent. “I’m an ex-Marine. My heart is in everything,” Cutts said. “I still want to do everything I once did. I’ve been fortunate. I’m an optimist.”

Survivor Story
John Conway Pleural mesothelioma

Navy Veteran and pleural mesothelioma survivor

Survivor Story

John Conway worked as a Navy boiler technician at the peak of the asbestos era, when ships heavily used asbestos products, particularly where he often worked. He then worked for the Merchant Marines for 24 years. “I grew up wanting to be in the Navy,” he said. “I was proud to serve. It was fun, too. It took me around the world three times. I never thought about any long-range danger.”

Read John’s Story

Secondhand Exposure to Asbestos

Secondary exposure happens when someone carries asbestos fibers on their skin, hair, clothing, footwear or tools. Those fibers could then spread into the air, putting those around them at risk of exposure. People in occupations with high contact and proximity to asbestos were most at risk of bringing home fibers on their bodies or gear. 

My mesothelioma was caused by my father’s work clothes. He had been a lagger and worked with asbestos all through my childhood. He died of mesothelioma in 1989.

The formerly widespread use of asbestos in all sorts of products inadvertently put many people at risk for primary and secondary exposure. For example, barbers and ceramics workers used talc contaminated with asbestos. Bringing these fibers home caused cancer in many of their family members.

Environmental Exposure

Living near large asbestos deposits in hilly or mountainous regions puts residents at risk of environmental exposure. Minimal amounts of microscopic fibers can linger in the air in these regions. This is most dangerous near former asbestos mines and manufacturing plants.

In June 2009, the United States Environmental Protection Agency declared a public health emergency in Libby, Montana. The hazard arose from an asbestos-contaminated vermiculite mine in the town. Thousands of Libby residents have been diagnosed with asbestos-related diseases, including mesothelioma. 

The risk of disease associated with living near asbestos mines or facilities is lower compared to occupational asbestos exposure. Research suggests encountering asbestos this way may account for 3% of all mesothelioma cases and about 19% of cases in women.

Dr. Jacques Fontaine and Dr. Virginia Wolf
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How Can I Reduce My Risk of Mesothelioma? 

Employers should be responsible for providing safe workplaces and preventing asbestos exposure, but there are steps you can take to help minimize your risk. Because occupational asbestos exposure is the primary cause of this cancer, the best way to prevent mesothelioma is to follow workplace safety regulations.

Report potential hazards. Talk to your employer about asbestos risks and the policies in place to mitigate those risks at your workplace.

Tips to Reduce Asbestos Exposure
  • Avoid wearing clothing, footwear and other work gear at home that could harbor asbestos fibers.
  • Hire a reputable professional asbestos abatement company to test and remove asbestos from your home.
  • Purchase talc-free cosmetics and personal care items.
  • Take care when purchasing vintage, antique or upcycled products and materials that historically contained asbestos.
  • Talk to your doctor about your work history and regularly schedule appropriate screenings for early detection.

Avoiding asbestos products, natural asbestos deposits and talc-containing products will limit your contact and risk of developing mesothelioma. Be cautious about DIY projects in older homes containing asbestos materials. Hire a professional asbestos abatement company to test and remove asbestos materials. 

If you or a loved one has a history of asbestos exposure, talk to your doctor about cancer screenings. Early detection offers the best opportunity for effective mesothelioma treatment.

Common Questions About Mesothelioma Causes

What type of asbestos exposure causes mesothelioma?

All types of asbestos exposure, including occupational, secondary and environmental, can cause mesothelioma. Every type of asbestos fiber, including chrysotile asbestos, can cause this cancer.

Who is most likely to get mesothelioma?

Men are more likely than women to receive a mesothelioma diagnosis. About 75% of people with mesothelioma are 65 years of age and older. This cancer is rare in people under age 45.

What symptoms may indicate I have mesothelioma?

Symptoms of mesothelioma include chest pain, shortness of breath, stomach pain, abdominal swelling, fatigue and weight loss. A mesothelioma doctor is the best specialist to see for diagnosis and treatment.

How long does it take for mesothelioma to develop?

Asbestos fibers turn healthy cells into cancer cells decades after exposure. The fibers initiate an inflammatory process that slowly causes genetic damage and eventually cancer 20 to 60 years later. Once tumors form, mesothelioma can quickly progress to stage 3 or 4 before causing symptoms.

Does smoking cause mesothelioma?

No, smoking does not cause mesothelioma. The primary cause of mesothelioma is exposure to asbestos fibers. While smoking and tobacco use are linked to lung cancer and other malignancies, they are not associated with an increased risk of mesothelioma.

Answered By: Anna Nowak, internationally renowned asbestos researcher and mesothelioma advocate.

Are there screenings available for mesothelioma?

If you have a history of asbestos exposure, speak to your doctor about screenings for mesothelioma as soon as possible. If you develop respiratory, abdominal or other mesothelioma symptoms, see your doctor right away. Initial mesothelioma symptoms can include shortness of breath, chest pain or abdominal distress. Patient Advocates can help connect you with a specialist for a diagnosis, second opinion and specialized treatment.

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