Asbestos and Cancer Risk

Asbestos is a known cause of cancer. Most people today don’t have contact with the high levels of asbestos that were common in some workplaces decades ago, but there are still places where you might be exposed to it.

Learning where asbestos is found, how you could be exposed, and what studies show can help you understand how it might affect your risk of cancer.

What is asbestos?

Asbestos is a group of minerals that occur naturally as bundles of tiny fibers. These fibers are found in soil and rocks in many parts of the world. Asbestos is made mostly of silicon and oxygen, along with small amounts of other elements.

Types of asbestos fibers

There are several types of asbestos fibers. Research suggests that the fiber size, shape, and strength may affect the level of risk.

• Amphibole asbestos fibers might be more harmful because they tend to be straighter and can travel deeper into the lungs and stay there for a long time. These include actinolite, tremolite, anthophyllite, crocidolite, and amosite fibers.
• Chrysotile asbestos fibers generally don’t travel as deeply into the lungs because of their spiral shape, but they are still linked to an increased risk of cancer.

What has asbestos been used for?

Asbestos fibers are strong and resistant to heat and many chemicals. They also don’t conduct electricity. Because of these properties, asbestos was once widely used in many building materials and products, including:

• Insulation
• Roofing shingles
• Floor and ceiling tiles
• Cement
• Textiles
• Auto brake and clutch parts

The use of asbestos in the United States has dropped sharply since the 1970s as more has been learned about its health risks. Although many uses have been restricted, older buildings and homes might still have materials containing asbestos.

Does asbestos cause cancer?

Studies have linked all types of asbestos to cancer.

What do expert agencies say?

In general, the American Cancer Society (ACS) does not determine whether something should be considered a carcinogen (something that can cause cancer). Instead, ACS looks to other respected organizations for help with this.

Based on current research, several expert agencies have made the following determinations:

• The International Agency for Research on Cancer (IARC), which is part of the World Health Organization (WHO), classifies all forms of asbestos as carcinogenic to humans.
• The US National Toxicology Program (NTP), a program of the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA), classifies asbestos as known to be a human carcinogen.
• The US Environmental Protection Agency (EPA) maintains the Integrated Risk Information System (IRIS), an electronic database on human health effects from exposure to various substances in the environment. The EPA classifies asbestos as a human carcinogen.

To learn more about how cancer causes are studied and classified, see How Do We Know What Causes Cancer? and Known and Probable Human Carcinogens.

What do lab studies show?

Lab studies are done using lab animals or cells in lab dishes. Lab studies provide strong evidence that asbestos can cause cancer. Research shows that asbestos fibers can cause ongoing inflammation, damage cellular DNA, and interfere with how cells grow and repair themselves. Studies in rodents have found that asbestos can lead to cancers such as mesothelioma and lung cancer through different routes of exposure.

What do studies in people show?

Studies in people compare groups to see if people with higher exposures are more likely to develop cancer. Studies have shown that exposure to asbestos raises the risk of some types of cancer. In general, the greater the exposure to asbestos, the higher the risk.

Mesothelioma

Mesothelioma is a rare type of cancer that affects the lining around the lungs or organs in the abdomen. Although it is uncommon in the general population, many studies have shown that mesothelioma risk is increased with asbestos exposure at work.

Mesothelioma usually takes a long time to develop. It’s often diagnosed 20 to 50 years after first exposure. The risk of mesothelioma doesn’t appear to go down over time after exposure and may last for the rest of the person’s life.

Lung cancer

Studies of certain types of workers have shown that asbestos exposure increases the risk of lung cancer over time. Lung cancer related to asbestos usually develops many years after a person is exposed.

For workers exposed to asbestos who also smoke, the lung cancer risk is even greater than adding the risks from these exposures separately.

Other types of cancer

Studies have shown that asbestos increases the risk of cancers of the larynx (voice box) and ovaries.

More recent research also suggests that asbestos might also increase the risk of certain cancers of the digestive system, including cancers of the esophagus, stomach, and colon and rectum. Scientists are still studying how asbestos might increase the risk of these cancers.

How are people exposed to asbestos?

People are usually exposed to asbestos by breathing in or swallowing asbestos fibers.

Breathing in asbestos fibers or dust: This is the most common type of exposure. It can happen when asbestos or asbestos-containing products are damaged or begin to break down. This can happen during mining or processing asbestos or manufacturing asbestos-containing products. It can also occur during construction, renovation, demolition, or maintenance work. People can breathe in asbestos fibers that are released and float in the air.

Swallowing asbestos: People might swallow asbestos fibers that have settled in food, water, or dust. They might also cough up inhaled fibers and swallow them.

Where exposure occurs

People with the highest exposures are often those who have worked in industries that used asbestos to make things, such as shipbuilding and insulation. Family members of asbestos workers can also be exposed when asbestos fibers are carried home on a worker’s clothing, shoes, or equipment.

Older homes and buildings may contain asbestos in insulation, roofing, or ceiling and floor tiles. These materials usually don’t pose a health risk as long as they stay intact and in good condition. Asbestos is usually safest when it’s sealed inside products such as walls or floor tiles and isn’t damaged or disturbed by activities such as drilling or remodeling.

Some people are exposed to very small amounts of asbestos in the environment because it occurs naturally in some rocks and soil. Asbestos can also enter air or water through natural erosion or breakdown of older asbestos-containing materials.

What about asbestos in talc products?

Talc is a mineral used in some cosmetic and personal care products, including talcum powder. Because talc and asbestos can naturally occur near each other, talc can sometimes be contaminated with asbestos.

In 1976, the US cosmetics industry adopted a voluntary method for testing talc for asbestos. This testing was not required by law, and the method has been criticized as not sensitive enough to detect low levels of asbestos.

Currently, there is no federal rule that requires companies to test cosmetic talc for asbestos. Testing is largely voluntary, though many manufacturers test their own talc. The FDA sometimes samples products on the market. When it last tested talc-containing cosmetics in 2023, it did not detect asbestos in the products sampled.

Concerns have been raised about whether long-term use of talc-based powders in the genital area may increase the risk of ovarian cancer, regardless of whether they include asbestos. The research on this is difficult to interpret because it is hard to separate the effects of the talc itself from possible past asbestos contamination. Researchers are still working to clarify this link. For more on this topic, see Talcum Powder and Cancer.

Are asbestos levels regulated?

Several US government agencies regulate asbestos levels and exposures.

The Occupational Safety and Health Administration (OSHA) sets legal limits on how much asbestos workers can be exposed to in the workplace. There is no safe level of asbestos. However, the risk generally increases with higher levels of exposure and longer durations of exposure. OSHA limits exposure to 0.1 fibers per cubic centimeter of air (f/cc) over an 8-hour workday, with a short-term limit of 1.0 f/cc over any 30-minute period.

Employers must check asbestos levels in the workplace and take steps to reduce exposure. They must provide personal protective equipment, such as respirators, when needed. There are also additional safety rules for construction and shipyard workers.

The EPA helps protect people from asbestos exposure in schools, public buildings, and the environment. It requires schools to check for asbestos and manage it safely. The agency also sets rules for the safe handling and disposal of asbestos-containing materials and helps limit asbestos fibers in the air and drinking water.

The Consumer Product Safety Commission (CPSC) has banned asbestos in certain consumer products, including artificial fireplaces and patching compounds used on walls and ceilings.

Can I avoid or limit my exposure to asbestos?

You can reduce your risk of asbestos exposure by taking the right precautions at work and at home.

If your job might expose you to asbestos, follow safety procedures and use the proper protective equipment. Talk with your employer or safety officer about any asbestos concerns at work.

If you live in an older home that might have asbestos-containing insulation or other materials, consider having it checked by a trained professional. Just having asbestos-containing materials in a home does not necessarily mean that they need to be removed. As long as the material is not damaged or disturbed, such as by drilling or remodeling, the fibers are not released into the air. Do not try to remove or disturb asbestos-containing material yourself, as this can increase exposure for you and others. Hire a contractor to do the work safely.

What should I do if I’ve been exposed to asbestos?

If you’ve been exposed to asbestos, your health risk depends on how much asbestos you were exposed to and for how long. People with higher or longer exposures may have a greater risk of certain cancers and other asbestos-related diseases, such as asbestosis (scar tissue in the lung).

There are steps you can take to help protect your health:

• If you smoke, try to quit. Smoking greatly increases the risk of lung cancer in people exposed to asbestos.
• Talk with your doctor about your exposure. They can help decide whether you need regular checkups, lung function tests, or imaging tests such as CT scans to look for signs of disease.
• Watch for possible symptoms of cancer or other lung problems. Tell your doctor if you develop symptoms such as shortness of breath, a new or worsening cough, coughing up blood, chest pain or tightness, trouble swallowing, or unexplained weight loss.
• Stay up to date on vaccines. Ask your doctor about vaccines that help protect against respiratory infections, such as flu, pneumonia, and COVID-19.

If you’ve been diagnosed with an asbestos-related cancer, you may be eligible for financial or medical assistance. Depending on your situation, help may be available through Medicare, workers’ compensation programs, or Veterans Affairs (VA) healthcare benefits.