Mesothelioma Causes & Risk Factors

What Causes Mesothelioma? 

Asbestos exposure is the No. 1 cause of mesothelioma. Mesothelioma develops decades after microscopic asbestos fibers are inhaled or ingested. The fibers get trapped in a thin layer of tissue called the mesothelium. This smooth tissue lines the lungs, abdomen, heart and testes.

Asbestos fibers can pierce this lining. They cause inflammation and damage to the mesothelial cells. Over time, this damages the DNA of your cells and can cause mesothelioma tumors to form.

Most mesothelioma cases are caused by asbestos exposure at work or in the military. Some people also develop mesothelioma because of secondhand contact. Workers have inadvertently brought asbestos home on their bodies, clothing or gear, exposing their families.

Asbestos-contaminated talc can also cause mesothelioma. Other risk factors can raise the chance of cancer in those exposed to asbestos. Examples include family history, genetics and exposure to radiation.

“Mesothelioma is caused by exposure to asbestos,” says Dr. Marcelo DaSilva, chief of thoracic surgery at AdventHealth Cancer Institute. “Patients inhale asbestos, which causes chronic inflammation that changes its DNA into a cancer cell.”

Mesothelioma Risk Factors

Asbestos exposure is the biggest risk factor for a mesothelioma cancer diagnosis. Risk factors are characteristics that increase the likelihood of developing a particular disease. Other risk factors include genetics, age, gender and other exposures.

Exposure to asbestos can occur in the workplace, older homes, public buildings and the environment. While many people know if they’ve been exposed to asbestos, others may not be aware of their exposure.

There are several types of asbestos exposure: Occupational, military, secondary and environmental. Asbestos fibers were used in construction, auto parts and machinery for their heat resistance. But they can break down and create toxic dust. Home exposure happens when homeowners or others in the house come in contact with older construction products that used asbestos.

Raeleen Minchuk, a peritoneal mesothelioma survivor from Canada, was exposed to asbestos in her grandparent’s home. She was just a baby when her grandfather renovated his home. Raeleen crawled on the floor covered with asbestos dust. At the time, the public wasn’t aware of the dangers of asbestos.

Occupational Asbestos Exposure

Occupational asbestos exposure poses the highest risk of disease. This is especially true for miners and factory workers who made asbestos products.

Construction workers and firefighters today encounter legacy asbestos when working in older buildings. The risk is high during renovation, demolition or disaster response. Other occupations at risk of mesothelioma include industrial, factory and textile mill workers. Shipyard, boiler and power plant workers also worked around many asbestos products.

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. The U.S. Centers for Disease Control recently reported a sharp rise in mesothelioma cases in women.

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

Military Asbestos 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 reduced fires on ships. It was also used in protective gear, like respirators and heat-resistant gloves, for operating gun turrets.

Retired Navy veteran John Conway worked as a boiler technician, and he remembers stripping asbestos insulation as part of his job. Decades later, John developed pleural mesothelioma. “It used to look like it was snowing down there,” John said.

Case Study: John Conway & Military Asbestos Exposure

John Conway was exposed to asbestos while serving in the Navy. Doctors diagnosed him with pleural mesothelioma more than 40 years later.

Occupational Exposure: John worked as a Navy boiler technician at a time when ships heavily used asbestos. He primarily served on 4 different Navy ships. Then he worked for the Merchant Marines for 24 years.

Latency Period and Diagnosis: He was diagnosed with mesothelioma in July 2012. A 40-year gap between exposure and diagnosis isn’t unusual for this disease. Mesothelioma usually takes 20 to 60 years to develop. Time from exposure to diagnosis is known as the latency period.

Treatment: Dr. David Sugarbaker, who was a leader in the field, treated John’s cancer. John had 9 rounds of chemo in Boston and Florida. Then he had surgery to remove the pleural lining around his lungs. All visible tumors on his chest wall were also removed.

Environmental Asbestos Exposure

Living near large asbestos deposits in hilly areas risks 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 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. Thousands of Libby residents have been diagnosed with asbestos-related diseases, including mesothelioma. 

The risk of disease from living near asbestos mines is lower than from working with asbestos. Research suggests that this may cause 3% of all mesothelioma cases and 19% of cases in women.

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Secondary Exposure

Secondary exposure happens when someone carries asbestos fibers home. It gets carried 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 with high-contact jobs with asbestos were most at risk. They could bring home fibers on their bodies, uniforms or work tools.

The widespread use of asbestos in many products puts thousands 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. Women and children are more likely to have secondary exposure.

Gender,  Age and Genetics

Men are more likely than women to develop mesothelioma. Men are also more likely to have occupational asbestos exposure. Mesothelioma occurred 2.4 times more often in men than in women in 2020. This is the most recent data from the U.S. Centers for Disease Control and Prevention and SEER. Women are more likely to be exposed to asbestos through contaminated talc used in talcum powder.

The CDC reported in 2020 that most people get diagnosed between ages 75 and 79. Mesothelioma risk increases with age because mesothelioma takes 20 to 60 years to develop after exposure. This does not mean that young people do not get mesothelioma from asbestos exposure. Cases of asbestos-related mesothelioma have occurred in teens and young adults in their 20s.

Genetic factors can increase the risk of various types of cancer. Mutations of a gene called BRCA-associated protein 1 (BAP1) often exist in mesothelioma cancer cells. These mutations can be inherited from a parent or acquired during a person’s lifetime. Mesothelioma is not inherited. But if a person inherits this specific mutation, it will increase their risk of mesothelioma.

Other Potential Risk Factors

Other risk factors include exposure to radiation, Simian Virus 40 and asbestiform minerals like erionite. Tobacco smoking, diet and nutrition are not risk factors for mesothelioma. But smoking combined with asbestos exposure significantly increases the risk of lung cancer.

Exposure to ionizing radiation may be a risk factor for mesothelioma. X-rays, gamma rays and other forms of ionizing radiation can increase the risk of different types of cancer. Exposure to high doses of radiation may be a risk factor for mesothelioma. Radiation therapy for cancer is an example. Low doses of radiation from X-rays, CT scans and occupational exposure are not risk factors.

Simian Virus 40 is a virus linked to several types of cancer, including mesothelioma. SV40 does not usually cause illness in humans and is not known to cause mesothelioma. However, research indicates that many mesothelioma cases show the presence of SV40 in cancer cells. Ongoing research will determine whether it is a risk factor for mesothelioma.

How to Lower Your Risk of Mesothelioma 

Preventing mesothelioma means reducing exposure to asbestos. It is the main cause of this cancer. Asbestos exposure at work is the main cause of this cancer. To prevent mesothelioma, we must follow asbestos workplace safety guidelines. 

“If you’ve been a construction worker or were repairing cars or were in the Navy, and you’re starting to experience shortness of breath or trouble breathing or pain in your chest, it’s important to speak about it with your physician,” says Dr. Jacques Fontaine, director of the Mesothelioma Research and Treatment Center at Moffitt Cancer Center.

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

If you develop respiratory, abdominal or other mesothelioma symptoms, see your doctor right away. Initial symptoms of mesothelioma 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.

Common Questions About Mesothelioma Causes

How much exposure to asbestos will cause mesothelioma?

Most people with asbestos exposure will never develop mesothelioma. However, any asbestos exposure can cause mesothelioma. Chronic exposure carries the highest risk, but even a single exposure can lead to mesothelioma.

How likely am I to develop mesothelioma?

Mesothelioma is a rare form of cancer. There are about 3,100 new cases per year in the U.S. There were 0.7 new cases per 100,000 people in 2018. Mesothelioma is very rare in people without any known asbestos exposure. High-risk occupations for asbestos exposure include construction, power generation, shipbuilding and industrial work.

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. Smoking and tobacco use are linked to lung cancer and other cancers. But, they are not linked to a higher risk of mesothelioma.

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

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