Mesothelioma Risk Factors

Understanding Mesothelioma Risk Factors

There are spaces, called cavities or sacs, in the body that hold different internal organs. For example, the lungs sit in the pleural cavity, the stomach in the peritoneal cavity and the heart in the pericardium sac.

All of these cavities are lined with a membrane called the mesothelium. This thin lining produces fluids that lubricate the space between the organ and the cavity wall, which allows for freer movement during processes like breathing, when the lungs fill up with air.

Mesothelioma is a cancer that affects these linings. Sometimes it is named for the cavity that it develops in. For example, mesothelioma in the lung cavity may be referred to as pleural mesothelioma. Other times, it is simply referred to as malignant mesothelioma.

Asbestos and Mesothelioma

A history of exposure to asbestos has been identified as a major risk factor for developing mesothelioma. Asbestos is a naturally occurring fibrous mineral that was found to have many useful industrial applications because of the fiber's strength, resistance to fire and heat as well as its low electrical conductivity.

In the past, asbestos was commonly used in homes, schools and in manufacturing. The properties of this silicate material were well-suited for use in insulation, floor and ceiling tiles, fire-proof gloves and even automobile products like brake pads, among other things.

The sharp, light crystalline fibers, when inhaled, may irritate and cause damage to the lungs and the membrane in the pleural (lung) cavity. Miners, mill workers and people working with asbestos for long periods of time are at the greatest risk for developing mesothelioma. However, it may take upwards of 20 to 30 years after the exposure before the cancer develops.

Today the risk of exposure for workers in the manufacturing industry is much less since asbestos, by and large, is no longer used in the United States. Although the use of asbestos has decreased dramatically since the late 1980's, asbestos may still be found in older buildings or products.

There has also been concern about asbestos in schools and workplaces. The risk of exposure to asbestos in older buildings may be minimal as long as asbestos dust does not get into the air. Nonetheless, precaution should be taken during the renovation of older buildings to reduce the risk of exposure to the fibers. (Note: The EPA has programs that regulate and manage asbestos in buildings, schools and products as mandated by the Asbestos Hazard Emergency Response Act (AHERA) of 1986).

The National Cancer Institute reports that about 3 out of 4 cases of mesothelioma are related to a worker's history of exposure to asbestos. In some cases it has been found that family members may be at risk if exposed to asbestos fibers on the clothing of a worker that has been exposed to asbestos.

However, there are other factors that may increase the risk of developing mesothelioma whether in combination with asbestos exposure or on their own. In some cases, people who have developed mesothelioma have had no known risk factors.

Other Risk Factors of Mesothelioma

Although asbestos is a major risk factor, there is evidence that other factors may also contribute to an increased likelihood for developing mesothelioma. As with many other types of cancer, having one or more risk factor does not mean you will get cancer. Having been exposed to asbestos, for instance, may increase the likelihood of pre-cancerous mutations occurring in the mesothelium (membrane lining), but researchers still have not identified an exact cause.

Some other mesothelioma risk factors include:

• SV40 - Between 1955 and 1963, some Polio vaccinations were infected with SV40 (simian virus 40). There is ongoing researching exploring the possibility that SV40 infections may have an effect on the development of mesothelioma. Although there is no conclusive evidence, there may be an overlap in the peak age range of those, 50 to 70 years old, who are diagnosed with mesothelioma and the timing of the exposure to SV40.
• Thorium dioxide - Up until the 1950's, thorium dioxide (Thorotrast) was injected into the chest or abdomen before an x-ray was taken to create contrast in the image. There may be a link between the thorium dioxide, followed by a high dose of radiation, and mesothelioma.
• Smoking - Although smoking is not a risk factor, some think that smoking in combination with asbestos exposure may increase the risk of developing mesothelioma.

The risk from long-term exposure does not decrease over time; rather, it may take over 20 years from the last exposure before cancer develops. Talk to your doctor if you or a loved one has a history of asbestos exposure.

NOTE: Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer. Not having risk factors doesn’t mean that you will not get cancer. If you think you may be at risk, you should discuss it with your doctor.

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