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A risk factor is anything that affects a person's chance of
getting a disease such as cancer. Different cancers have different risk
factors. Some risk factors, such as smoking, can be controlled. Others,
like a person's age or family history, can't be changed. But risk
factors don't tell us everything. Having a risk factor, or even several
risk factors, does not mean that you will get the disease. And some
people who get the disease may not have had any risk factors.
Researchers have found some factors that increase a person's
risk of mesothelioma.
Asbestos
The main risk factor for mesothelioma is contact with
asbestos. In fact, most cases of mesothelioma have been linked to
asbestos in the workplace. In the past, asbestos was used in
insulation, and in other things like floor tiles, door gaskets,
roofing, patching compounds, and more. Since asbestos is a natural
mineral, it can also be found in dust and rocks in certain parts of the
United States. Most asbestos use stopped after 1989, but it is still
used in some products.
When asbestos fibers are breathed in, some can travel to the
ends of the small air passages and reach the lining of the lungs. There
they can damage the cells lining the lungs, and with time lead to
pleural mesothelioma. If swallowed, these fibers can also reach the
lining of the abdominal cavity where they play a part in causing
peritoneal mesothelioma.
People who may be at risk for asbestos exposure include some
miners, factory workers, makers of insulation, railroad workers, ship
builders, gas mask makers, and construction workers. Studies have shown
that family members of people exposed to asbestos at work have an
increased risk of mesothelioma, too, because asbestos fibers are
carried home on the clothes of the workers.
Asbestos was used in the insulation of many older homes and
public buildings around the country, including some schools. Because
the asbestos is contained within the building materials, a large amount
is not likely to be found in the air. The risk is thought to be much
less unless the asbestos is somehow released into the air, such as when
building materials begin to decompose over time, or during remodeling
or removal.
The risk of getting mesothelioma depends on how much asbestos
a person was exposed to and for how long. Mesotheliomas take a long
time to develop. The time between the first exposure and finding the
disease is often between 20 and 50 years. Another important point about
asbestos once you have been exposed to asbestos, the risk of
mesothelioma appears to be lifelong and it does not go down over time.
To learn more about asbestos, see the ACS document, Asbestos.
Radiation
There is some evidence linking thorium dioxide (Thorotrast) to
mesothelioma. Thorotrast is a material that was once used in certain
x-rays. It has not been used for many years.
SV40 virus
Some studies have suggested that infection with simian virus
40 (SV40) might increase the risk of mesothelioma. Some polio vaccines
prepared between 1955 and 1963 were contaminated with SV40. Research
into this question is still going on.
Last Medical Review: 04/01/2009
Last Revised: 04/01/2009
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