Mesothelioma Causes & Risk Factors

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Asbestos is the primary cause of mesothelioma. The cancer is caused after years of damage from asbestos fibers getting lodged in the lining of the lungs or abdomen. Common symptoms include dry cough and shortness of breath. Risk factors include exposure to asbestos products at home, the workplace and in the military.

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Dr. Jacques Fontaine talks about the different people who are at risk of developing mesothelioma.
Dr. Jacques Fontaine talks about the different people who are at risk of developing mesothelioma.

What Causes Mesothelioma?

Asbestos causes mesothelioma. Inhaled asbestos fibers damage DNA, causing inflammation and scarring. Mesothelioma develops after decades of asbestos exposure.

Mesothelioma is caused when airborne asbestos fibers are inhaled and become lodged in the pleura. Over time, the asbestos fibers cause inflammation, scarring and eventually lead to mesothelioma cancer.

Diagram showing how asbestos exposure affects the body
Diagram of mesothelioma causes by location.

Mesothelioma is caused when airborne asbestos fibers are inhaled and become lodged in the pleura. Mesothelioma will eventually develop after decades of asbestos fibers causing inflammation and scarring.

When the fibers travel to different parts of the body, it results in different types of mesothelioma.

Mesothelioma was virtually unknown until the 20th century. After decades investigating the disease, medical researchers identified the cause: Asbestos exposure. Mesothelioma incidence rates rose as industries expanded the use of asbestos.

Research studies proved inhaling or swallowing microscopic asbestos fibers can start a chain reaction that leads to several types of cancer.

In 2012, the International Agency for Research on Cancer reconfirmed asbestos exposure as the leading cause of mesothelioma. All forms of asbestos cause the disease.

Primary Risk Factors for Mesothelioma

  • Working at an asbestos mine or asbestos-processing plant
  • Working in a high-risk occupation such as construction or heavy industry
  • Serving on military ships or facilities built with products containing asbestos
  • Living in a residential area near an asbestos mine or contaminated site
  • Disturbing asbestos products during a home renovation without proper safety measures

Where Does Asbestos Exposure Occur?

Asbestos exposure primarily happens in a workplace setting. It can also happen at home and in the natural environment.

Asbestos was widely used in thousands of commercial, industrial and domestic products. Examples include drywall, insulation, piping, glues and adhesives, ceiling tiles, cement and shingles.

Workers who manufactured or used these products were exposed to asbestos on the job. Others, including workers’ family members, faced secondary exposure at home. Environmental exposure happened in communities that mined or processed asbestos.

Quick Fact:

Asbestos removal is highly regulated, and the government fines people and businesses that ignore the rules. Workplace asbestos exposure is still a hazard at job sites where safety procedures are not followed.

Past Occupational Exposure

The risk for asbestos-related illnesses is highest for people who worked with the raw mineral or with asbestos-containing products on a daily basis.

High-Risk Occupations

  • Shipyard workers
  • Construction workers
  • Power Plant workers
  • Chemical Plant workers
  • Industrial workers
  • Insulators
  • Boiler workers
  • Auto mechanics

Risk Factors in Present-Day Jobs

Construction tradesmen and firefighters can be exposed to asbestos while working in old homes and structures built with contaminated materials. Exposure can happen during a renovation, demolition or disaster response.

When old buildings are destroyed without safety precautions, airborne asbestos fibers can contaminate the surrounding area. Even new buildings contain asbestos products such as roofing materials.

Firefighters, contractors, demolition workers, electricians and plumbers are at high risk of exposure to asbestos in old buildings.

Secondhand Exposure

When the asbestos industry was booming, families of workers were also at great risk. Workers often came home with asbestos fibers on their hair, work clothes, shoes and tools. This exposed family members to the toxic substance and increased their risk for related diseases.

Environmental Exposure

Because asbestos is a naturally occurring mineral, people living near large deposits in hilly or mountainous regions also face exposure. Minimal amounts of the mineral can fill the air in these regions. Still, environmental exposure is most dangerous near former asbestos mines.

Judy Goodson diagnosed with peritoneal mesothelioma in 2013

“My father worked in steel mills for years and I remember washing his clothes which were covered in dust.”

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How Does Mesothelioma Develop?

Mesothelioma can develop as a result of DNA damage caused by asbestos fibers.

Once asbestos is inhaled, the body has a hard time getting rid of the fibers.

The fibers become lodged in tissues and accumulate with repeated exposure. After many years, these fibers may cause cancerous changes to surrounding cells.

Mesothelioma starts in mesothelial cells, which make up the protective membranes of the mesothelium that cover the lungs, abdomen and heart.

Four stages of mesothelioma tumors forming on the lungs.
Tumors tend to form a sheath around the affected lung.

DNA Damage Caused by Asbestos Fibers

  • Inflamed Cells: Fibers inflame and irritate mesothelial cells, leading to irreversible scarring, cellular damage and cancer.
  • Genetic Changes: Fibers enter mesothelial cells and disrupt their life cycle, causing genetic changes that lead to cancer.
  • Cancerous Mutations: Asbestos causes the production of free radicals, which are molecules that damage DNA and cause healthy cells to mutate.
  • Uncontrolled Growth: The fibers trigger the production of oncoproteins, which block genes that protect cells from growing uncontrollably and forming tumors.

Other Mesothelioma Risk Factors

  • Exposure to other fibrous minerals such as erionite.
  • Exposure to radiation.
  • Receiving a polio vaccine between 1955 and 1963 that was contaminated with simian virus 40 (SV40).
  • Genetic factors that increase the likelihood of developing cancer.

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Differences Between Mesothelioma Causes & Risk Factors

A risk factor is anything that increases the odds of developing a disease. A cause is the contributing factor that leads to a disease.

For example, although men are much more likely to develop mesothelioma than women, gender alone cannot cause the cancer.

Often, multiple risk factors are involved in the development of mesothelioma.

The duration of asbestos exposure plays a role. While the World Health Organization says no amount of asbestos exposure is safe, it is usually heavy, repeated exposure over many years that leads to asbestos-related illnesses.

A study in the American Journal of Epidemiology found the longer someone works in a job that involves asbestos exposure, the higher their risk of mesothelioma becomes.

Dose-Response Relation at Low Levels of Asbestos Exposure in a French Population-based Case-Control Study.
Years of Occupational Asbestos Exposure Increase in Risk of Mesothelioma
1-7 1.7 times more likely
8-19 2 times more likely
20+ 5.4 times more likely

The link between asbestos exposure and mesothelioma is so strong that it can be difficult for researchers to tell if any other risk factors can cause mesothelioma on their own. Although scientists continue to study this topic, and they know other fibrous minerals cause mesothelioma, exposure to asbestos remains the most clearly defined cause.

Is Smoking a Risk Factor for Mesothelioma?

No, studies show cigarette smoking is not a risk factor for mesothelioma. However, those who smoke and are regularly exposed to asbestos are much more likely to develop asbestos-related lung cancer.

Some studies reveal that smokers exposed to asbestos are upwards of 90 times more likely to develop lung cancer.

Researchers also found smoking can weaken lungs and reduce the body’s ability to dispose of asbestos fibers trapped inside. Smoking also aggravates asbestosis.

Preventing and Detecting Mesothelioma

The best way to prevent mesothelioma is to follow workplace safety regulations and protect yourself by learning more about how you might be exposed to asbestos at work and at home. Be cautious of materials in old homes that may contain asbestos.

If you think a past job or home repair project exposed you to asbestos, you should seek regular medical exams to check for signs of asbestos-related diseases.

If you or a loved one has a history of asbestos exposure — especially in the workplace — don’t wait for symptoms to arise. Instead, be proactive and talk to your doctor. Early detection offers the best opportunity for effective treatment.

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Registered Nurse and Patient Advocate

Karen Selby joined Asbestos.com in 2009. She is a registered nurse with a background in oncology and thoracic surgery and was the regional director of a tissue bank before becoming a Patient Advocate at The Mesothelioma Center. Karen has assisted surgeons with thoracic surgeries such as lung resections, lung transplants, pneumonectomies, pleurectomies and wedge resections. She is also a member of the Academy of Oncology Nurse & Patient Navigators.

Walter Pacheco, Managing Editor at Asbestos.com
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Last Modified June 20, 2019

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