Mesothelioma Causes

Quick Summary

Asbestos exposure is the only proven cause of malignant mesothelioma. Inhaled or ingested asbestos fibers can mutate cells in the linings of the lungs, abdomen, or heart, causing mesothelioma tumors. Because it takes 20-50 years for mesothelioma to develop after exposure, veterans are being diagnosed decades after they were exposed during military service.

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What Causes Mesothelioma?

Inhaling or ingesting asbestos fibers is currently the only known cause of mesothelioma. Asbestos is an extremely durable, naturally occurring mineral. Asbestos fibers are light and can float in the air for long periods, so they’re easy to inhale or ingest unintentionally.

Exposure to asbestos can happen in three primary ways, including:

  1. Occupationally: This is the most common type of asbestos exposure. Many mesothelioma patients had past on-the-job asbestos exposure.
  2. Secondhand: People exposed to asbestos in their occupation may have unintentionally exposed their family members as well. Asbestos fibers can get stuck to clothing. These fibers may be released at home where other people can breathe the fibers. This is called secondhand exposure.
  3. Naturally: Asbestos is a naturally occurring mineral. There are deposits of the fibers in some parts of America. People living near asbestos deposits or mines may breathe in the fibers nearby.

Asbestos fibers are like tiny needles that bore deep into body tissues where they are not easily dislodged or coughed out. Over time, asbestos fibers cause inflammation and scarring of body tissues. Prolonged irritation may eventually change the DNA of nearby cells, resulting in cancer.

Once asbestos fibers enter the body, they can remain there for decades before mesothelioma develops. The process of initial asbestos exposure to the development of mesothelioma can take 20 to 50 years, which is why symptoms take so long to show up after asbestos exposure.

Inhaled fibers eventually migrate to the lining of the lungs or the lining of the heart while ingested fibers can migrate to the peritoneum, the lining of the abdominal cavity. As a result, mesothelioma can develop in the lining of the lungs, abdomen, or heart.

How Mesothelioma Develops

Cancers like mesothelioma develop when something alters the DNA inside cells. DNA mutations cause cells to grow and divide uncontrollably.

Normal cell DNA tells the cells how to grow and develop, when to divide, and when to die. When asbestos fibers damage the DNA of otherwise healthy mesothelial cells, the affected cells stop behaving as they should. Instead, they continue to divide and grow when they are not supposed to. These mutated cancer cells grow uncontrollably to invade healthy tissue, form mesothelioma tumors, and spread throughout the body.

When asbestos fibers are inhaled, they travel through the chest wall to the lining of the lungs, called the pleura, and settle there permanently. The needle-like fibers irritate the tissues for many years until cell DNA becomes damaged, and malignant pleural mesothelioma tumors begin to form.

If the asbestos fibers are swallowed instead of inhaled, they can become lodged in the membranes that line the abdominal cavity and organs, called the peritoneum. Prolonged inflammation of the abdominal lining can eventually lead to peritoneal mesothelioma.

It’s unclear at this point exactly how asbestos travels to the heart lining, called the pericardium, to cause pericardial mesothelioma. It may involve either inhaling or ingesting asbestos fibers and may depend on the unique patient. Pericardial mesothelioma is the rarest form of the disease, and experts have a limited understanding of its pathology (how it develops).

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Finding the Link Between Asbestos and Mesothelioma

Asbestos fibers are extremely strong, heat-resistant, and resilient against chemical wear. Because of these durable properties, the use of asbestos was common in many products like insulation, floor tiles, roofing, and brake linings. This was before we knew that asbestos was dangerous.

Medical evidence linked asbestos to mesothelioma in the mid 20th century, but the connection wasn’t formally established until much later. The mineral remained uncontrolled by federal law until the late 1970s when it became undeniably clear that asbestos exposure causes mesothelioma.

The Environmental Protection Agency (EPA) banned certain asbestos products in 1973.

Asbestos was frequently used in military applications before this period. Because of its durability, asbestos was a staple product in vehicles, ships, tanks, buildings, and aircraft. Veterans who served in the military during the 20th century may have experienced long-term asbestos exposure in various capacities.

All types of asbestos are considered known human carcinogens by the World Health Organization, the International Agency for Research on Cancer, the U.S. Department of Health and Human Services, and the U.S. Environmental Protection Agency. Sufficient scientific and medical evidence has shown that asbestos causes mesothelioma.

Where Is Asbestos Found?

Asbestos was used throughout the 20th century in thousands of industrial and home applications.

Since asbestos was widely used in the military, veterans are one of the most at-risk groups. Veterans make up 30% of all mesothelioma cases. Branches of the military that were most significantly affected by asbestos include the Navy, Coast Guard, Air Force, Army, and Marines. Certain non-military occupations also presented a high risk of asbestos exposure.

Some occupations with the highest an increased risk of asbestos exposure include:

  • Auto Mechanics: People who were involved in manufacturing cars or repairing brakes may have been exposed to asbestos used in automobile parts.
  • Boilermakers: Boilermakers may have come into contact with asbestos used to insulate water heaters.
  • Brick and Stone Masons: People who worked with brick and stone may have inhaled asbestos fibers found in bricks and asbestos dust used in mortar.
  • Bulldozer Operators: During building demolitions, bulldozer operators may have inhaled airborne asbestos fibers that were released from building insulation.
  • Carpenters and Construction Workers: Carpenters were frequently in contact with asbestos used in insulation, flooring, and roofing materials.
  • Factory Workers: People working in factories producing asbestos-containing products may have been directly or indirectly exposed to airborne fibers. Asbestos was also used in factory machines and transportation belts.

Today, some occupations still put people at higher-than-average risk of asbestos exposure. Firefighters, electricians, HVAC workers, construction workers, and automobile mechanics may still be exposed to asbestos on the job.

Environmental Asbestos Exposure

Asbestos mineral deposits are found in rock and soil. Certain areas of the United States contain uncommonly high amounts of environmental asbestos. People who live near these mineral deposits have a higher risk of developing mesothelioma.

There are two main areas in the U.S. with high levels of natural asbestos — El Dorado Hills, California and Libby, Montana.

Most of California’s counties contain asbestos deep underground. In El Dorado Hills, rocks near the surface of the ground contain a particularly dangerous form of asbestos called tremolite. Libby was home to an asbestos-contaminated vermiculite mine, which was declared a public health hazard in 2009. The asbestos mine, owned by W.R. Grace & Company at the time, has since been cleaned up.

Other Asbestos-Related Diseases

Asbestos can destroy healthy cells in unexpected ways, causing other illnesses besides mesothelioma. Some other health problems associated with asbestos exposure include asbestosis, pleural disease, and lung cancer.

  • Asbestosis is a benign (non-cancerous), chronic lung disease caused by prolonged exposure to asbestos. When inhaled, asbestos fibers can become lodged in the alveoli — tiny sacs in the lungs that process oxygen. This makes it harder to breathe. Over time, asbestosis can result in lung tissue scarring, which can restrict breathing even more.
  • Pleural disease is also a benign condition. Asbestos fibers cause changes to the lining of the lungs, or pleura, which may become inflamed and thickened. Pleural disease can also cause fluid buildup in the pleural space. Both of these issues make it harder for the lungs to expand while inhaling.
  • Another type of cancer caused by asbestos is lung cancer. Asbestos fibers can pierce the lungs themselves and damage cell DNA over time, leading to the development of cancerous cells in lung tissue. This is not the same as mesothelioma.

Most cases of mesothelioma are caused by occupational asbestos exposure, making certain workers more at-risk of asbestos-related diseases than the average person. Still, anyone with a possible history of asbestos exposure should monitor themselves for symptoms of mesothelioma, as there are many cases of secondary exposure.

People Worried About Their Asbestos Exposure

Many people who worked in the construction and manufacturing trades have been exposed to asbestos, and some of them worry that they might develop an asbestos-related disease. Veterans may be particularly concerned about their future health since they have a higher risk of developing mesothelioma.

Veterans who served in certain branches of the military are more likely to have a history of asbestos exposure. If you worked in the Army, Navy, Air Force, Coast Guard or Marine Corps, you might have been exposed to asbestos. Shipyard workers, mechanics, miners, and construction workers have an exceptionally high risk of past exposure.

Your risk of developing mesothelioma increases with the amount of time you were exposed to asbestos. Even small amounts of asbestos can cause mesothelioma after many years of regular exposure. However, it has been well-established that there is no safe amount of asbestos exposure.

It’s also important to consider the time period in which you worked in risky occupations. Veterans who served in the military before 1980 were likely exposed to more asbestos than those who served later on. Even after asbestos use was controlled, many buildings, vehicles, and machinery still contained asbestos.

If you’re concerned about your history of asbestos exposure, you should visit your doctor or an oncologist. Your doctor will review your symptoms and exposure history and decide if you need further tests.

Some preventative measures can reduce your risk of mesothelioma and other asbestos-related diseases: 

  • Visiting the doctor for regular medical exams
  • Getting vaccinated against the flu and pneumonia
  • Making a plan to quit smoking
  • Avoiding all future exposure to asbestos

Why Were People Exposed to Asbestos?

Unfortunately, the majority of companies using asbestos in the mid to late 20th century knew that asbestos was dangerous. There is evidence that countless corporations continued using asbestos in their products after conducting independent research on the mineral and finding that it was cancer-causing.

Asbestos companies decided that the affordability and abundance of asbestos outweighed the costs of potential lawsuits. These companies continued to supply the military with asbestos-containing materials that eventually exposed countless service members.

Eventually, public research confirmed the dangers of asbestos. Measures were taken to reduce occupational exposure to asbestos during the second half of the 20th century. However, the mineral was still used in products for years. As the link between asbestos and health problems became public knowledge, people began filing lawsuits against their former employers.

Taking Control of Your Mesothelioma Diagnosis

When you know more about mesothelioma risk factors, you can better understand the disease, how it affects your body, and what can be done to treat it. Your asbestos exposure history is an important factor in determining your diagnosis and developing the best course of treatment for your illness.

Here are some things to remember about the causes of mesothelioma:

  • Asbestos is the only proven cause of mesothelioma
  • Most people were exposed to asbestos in their jobs
  • Veterans are more likely to develop mesothelioma because asbestos was widely used in most military branches

Mesothelioma is a devastating disease that can be extremely expensive to treat. Fortunately, there is help for veterans who developed mesothelioma after being exposed to asbestos in the military.

Contact the Mesothelioma Veterans Center for help finding top treatment options.

Veterans Support Team
Todd Gersten, MD PhotoReviewed by:Todd Gersten, MD

Double Board-Certified Oncologist and Hematologist

  • Fact-Checked
  • Editor

Todd Gersten, MD is a double board-certified medical oncologist and hematologist specializing in general adult oncology and hematologic disease. He is a physician partner with the Florida Cancer Specialists and practices in Wellington, Florida.

Dr. Todd Gersten is an independently paid medical reviewer.

Christopher Dryfoos PhotoWritten by:

Contributing Author

Christopher Dryfoos is a journalist and member of the American Medical Writers Association (AMWA). As the grandson of the U.S. Navy’s first forensic pathologist, he aims to help veterans with mesothelioma access needed care.

View Sources

Agency for Toxic Substances and Disease Registry. CDC. “Health Effects of Asbestos.” Retrieved from: Accessed on August 31st, 2017.

Environmental Protection Agency. “Superfund Site: Libby Asbestos Site.” Retrieved from: Accessed on August 31st, 2017.

Mayo Clinic. “Asbestosis Symptoms and Causes.” Retrieved from: Accessed on August 30th, 2017.

Mayo Clinic. “Mesothelioma Causes.” Retrieved from: Accessed on August 30th, 2017.

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