What Is the Primary Cause of Mesothelioma? 

Asbestos exposure is the primary cause of mesothelioma, accounting for more than 80% of mesothelioma cases. Most people diagnosed with mesothelioma experienced asbestos exposure from their jobs or military service. 

Key Facts About the Causes of Mesothelioma
  • Asbestos exposure causes about 50% of all occupation-related cancer deaths.
  • Occupational asbestos exposure is the No. 1 cause of mesothelioma worldwide.
  • Out of all people with heavy, prolonged exposure to asbestos, 8% to 13% develop mesothelioma.
  • Secondary asbestos exposure accounts for approximately 15% of mesothelioma cases in women.
  • A smaller number of people with mesothelioma developed it through secondhand exposure. Secondary exposure is sometimes called take-home exposure because the asbestos was brought home on clothing or gear and exposed workers’ families.

    “The majority of patients we speak with do know how they were exposed to asbestos. For those who don’t, we discuss the main categories of exposure. Sometimes this makes a light go off and they realize how they were exposed and the most likely cause of their mesothelioma.”
    Danielle DiPietro
    Patient Advocate and VA-accredited claims agent

    How Does Asbestos Cause Mesothelioma?

    The mesothelium is a protective lining in the body made up of mesothelial cells that can be damaged by asbestos fibers. Exposure to these fibers leads to chronic inflammation of the lining and an accumulation of genetic mutations in mesothelial cells. 

    Over time, scar tissue plaques develop on the lining. Mesothelioma tumors originate from these scar tissue plaques.

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

    Asbestos fibers that embed in the lining of the lungs can cause pleural mesothelioma. When the fibers get stuck in the abdominal cavity, they may cause peritoneal mesothelioma. Asbestos fibers may also embed in the pericardium surrounding the heart or the membrane that covers the testes, though pericardial and testicular mesothelioma are both very rare.

    Mesothelioma Risk Factors and Sources of Asbestos Exposure

    Occupational asbestos exposure is the No. 1 cause of mesothelioma. It’s the main factor for several asbestos-related illnesses, including asbestosis and pleural plaques.

    Exposure to asbestos, a natural mineral, was common from the 1940s through the 1970s when it was widely used in a variety of industrial and construction applications. In many cases, manufacturers didn’t tell their workers about the dangers of asbestos. 

    Most mesothelioma risk factors involve different sources of asbestos exposure. Your risk of developing cancer increases with the duration and intensity of your exposure. This is known as a dose-response relationship between asbestos and disease development.

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

    Dr. Snehal Smart, a Patient Advocate at The Mesothelioma Center, said some people don’t recall prior exposure to asbestos.

    “In past years, most patients knew exactly how they were exposed to asbestos. Recently, however, many patients aren’t as sure initially,” Smart said. 

    After learning more about the types of asbestos exposure, Smart said some people recall “secondhand exposure living with someone who worked around asbestos or maybe their own talcum powder exposure.” 

    DiPietro agreed, and added, “In one case, a woman was exposed to asbestos in the school where she worked as a teacher. But most people who aren’t initially certain of the source of exposure are women or patients under the age of 50.” 

    Occupational Exposure

    example of chrysotile asbestos ore, showing natural fibrous habit and greenish coloration.
    A sample of chrysotile asbestos showing the mineral’s natural fibers.

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

    Military Exposure

    Veterans also experience higher rates of mesothelioma. 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 heat-resistant gloves used for operating gun turrets and in respirators.

    David Cutts, a pleural mesothelioma survivor, served three 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.”

    The Honoring Our PACT Act of 2022 expanded access to health care and disability benefits for veterans harmed by toxic exposures, such as water contamination at Marine Corps Base Camp Lejeune. Advocates hope the PACT Act will streamline the VA process for veterans, increase the list of presumptive conditions included for benefits and expand health care eligibility.

    “This is long overdue, and hopefully will lead to more acknowledgment of the hazards that veterans were exposed to during service, including asbestos exposure, Agent Orange and burn pits. The PACT Act will finally make it easier for veterans and families exposed to toxic chemicals at Camp Lejeune to access medical and financial assistance.”
    Aaron Munz
    Director of the Veterans Department at The Mesothelioma Center.

    Secondhand Exposure

    Secondary exposure happens when asbestos fibers on someone’s skin, hair, clothing, footwear or tools put others at risk. People in occupations with high asbestos exposure were most at risk of bringing home asbestos on their body or gear. Their loved ones would then inhale or ingest these fibers, causing mesothelioma and related diseases.

    Barbers and ceramics workers used talc contaminated with asbestos. Bringing these fibers home caused cancer in many of their family members.

    Peritoneal mesothelioma survivor Tamron Little was exposed through a family member. 

    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 exposure is most dangerous near former asbestos mines and manufacturing plants.

    In June 2009, the U.S. Environmental Protection Agency declared a public health emergency in Libby, Montana. The hazard arose from an asbestos-contaminated vermiculite mine in the town. The agency has since cleaned up the area, and Montana received $18.5 million from the former mine owner to settle claims for environmental damages. Despite the effort, thousands of residents have been diagnosed with asbestos-related diseases, including mesothelioma. 

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

    How Can I Reduce My Risk of Mesothelioma? 

    Because occupational asbestos exposure is the primary cause of mesothelioma, the best way to prevent mesothelioma is to follow workplace safety regulations and report potential hazards. Talk to your employer about asbestos risks and policies in place to mitigate those risks at your workplace.

    Additional tips for reducing your mesothelioma risk include:
    • 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.

    The keys to preventing mesothelioma are understanding sources of asbestos exposure and taking precautions to avoid it. Avoiding asbestos products, natural asbestos deposits and talc-containing cosmetics will limit your exposure and risk of developing mesothelioma.

    Diagram showing how asbestos develops into pleural and peritoneal mesothelioma
    Diagram shows how pleural and peritoneal mesothelioma are caused.

    Be cautious of older homes containing asbestos materials. Hire a professional asbestos abatement company that can 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.

    When Should I Be Tested for Mesothelioma?

    If you develop respiratory or digestive symptoms of mesothelioma and have a history of asbestos exposure, see a doctor as soon as possible. This action could help you obtain an early diagnosis. 

    Mesothelioma symptoms may not show up until 20 to 60 years after exposure. Initial mesothelioma symptoms can include shortness of breath, chest pain or abdominal distress. Make sure to describe your asbestos exposure history to your doctor and request testing for asbestos-related diseases. Doctors will order imaging scans, blood tests and other tests based on your history of asbestos exposure to determine if you have mesothelioma. 

    General oncologists commonly misdiagnose this cancer as another disease or malignancy. Ask for a referral to a mesothelioma specialist to avoid a misdiagnosis and ensure access to the best 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 be diagnosed with mesothelioma. 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 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?

    Smoking often gets mistaken as a cause or risk factor of mesothelioma. Smoking cigarettes and asbestos exposure together elevate the risk of lung cancer. Smoking does not increase the risk of developing mesothelioma among those exposed to asbestos.

    Does SV40 cause mesothelioma?

    Evidence for SV40 as a possible cause for mesothelioma is conflicting. Researchers believe SV40 can’t cause mesothelioma 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 simian virus 40.  Higher rates of cancer have not been reported in those who received polio vaccines contaminated with SV40.