of the major risk factor involved in the development of mesothelioma
is working with asbestos. A history of asbestos exposure at
work is reported in about 70 percent to 80 percent of all cases.
However, mesothelioma has been reported in some individuals
without any known exposure to asbestos.
Asbestos and Mesothelioma Risk
Asbestos is the name of a group of minerals that occur naturally
as masses of strong, flexible fibers that can be separated into
thin threads and woven. Asbestos has been widely used in many
industrial products, including cement, brake linings, roof shingles,
flooring products, textiles, and insulation. If tiny asbestos
particles float in the air, especially during the manufacturing
process, they may be inhaled or swallowed, and can cause serious
health problems. In addition to mesothelioma, exposure to asbestos
increases the risk of lung cancer, asbestosis (a noncancerous,
chronic lung ailment), and other cancers, such as those of the
larynx and kidney.
Asbestos has been mined and used commercially since the late 1800s.
Its use greatly increased during World War II. Since the early
1940s, millions of American workers have been exposed to asbestos
dust. Initially, the risks associated with asbestos exposure were
not known. However, an increased risk of developing mesothelioma
was later found among shipyard workers, people who work in asbestos
mines and mills, producers of asbestos products, workers in the
heating and construction industries, and other tradespeople. Today,
the U.S. Occupational Safety and Health Administration (OSHA) sets
limits for acceptable levels of asbestos exposure in the workplace.
People who work with asbestos wear personal protective equipment
to lower their risk of exposure.
The risk of asbestos-related disease increases with heavier exposure
to asbestos and longer exposure time. However, some individuals
with only brief exposures have developed mesothelioma. On the other
hand, not all workers who are heavily exposed develop asbestos-related
There is some evidence that family members and others living with
asbestos workers have an increased risk of developing mesothelioma,
and possibly other asbestos-related diseases. This risk may be
the result of exposure to asbestos dust brought home on the clothing
and hair of asbestos workers. To reduce the chance of exposing
family members to asbestos fibers, asbestos workers are usually
required to shower and change their clothing before leaving the
Smoking and Mesothelioma Risk
Smoking does not appear to increase the risk of mesothelioma. However,
the combination of smoking and asbestos exposure significantly
increases a person's risk of developing cancer of the air passageways
in the lung.
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