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August 29, 2001
Information on Asbestos, CAS#1332-21-4
By Maureen Alvarez
CIH, CSP
Between 1940 and 1980, an estimated 27 million
Americans workers had an occupational exposure to asbestos
that could result in health effects. The Department of Health
and Human Services (DHHS) has determined that asbestos is
a known carcinogen. So, what is asbestos? What are the health
effects? Am I at risk?
What is Asbestos?
Asbestos is a naturally occurring mineral found
in soil and rock in some areas of the United States. The
six types of asbestos are actinolite, amosite, anthophyllite,
chrysotile, crocidolite, and tremolite. These minerals are
made up of fibers that vary in size and shape.
Asbestos fibers are resistant to heat and most
chemicals. Because of this, asbestos fibers are used for
a wide range of manufactured goods, mostly roofing shingles,
insulation material, ceiling and floor tiles, paper products,
asbestos cement products, friction products (automobile clutch,
brake, and transmission parts), textiles, packaging, gaskets,
and coatings.
How would I be exposed to asbestos?
Inhalation of asbestos fibers is the method
of exposure that is most likely to cause adverse health effects
for people. Workers in industries that use asbestos or products
containing asbestos (such as building materials), may inhale
fibers that are suspended in the air. Workers may also carry
asbestos fibers home on their clothes, where family members
might come into contact with asbestos by inhaling the fibers.
Also, people who live or work near asbestos-related operations
may inhale asbestos fibers that enter the air because of releases
of materials into the environment. Generally, asbestos fibers
are thin fibers too small to be seen; as they float in the
air, they can easily be inhaled. People may also swallow
asbestos fibers if they eat in areas where asbestos fibers
are in the air or if they drink water contaminated with fibers.
Homes and businesses insulated with material containing asbestos
may also be a source of exposure.
What recommendations has the federal government made
to protect human health?
The federal government has taken a number of
steps to protect citizens from exposure to asbestos. First,
on July 12, 1989, the EPA established a ban on new uses of
asbestos. Uses established before this date are still allowable.
Second, EPA has established regulations that require school
systems to inspect for asbestos and, if damaged asbestos is
found, to eliminate or reduce the exposure, either by removing
the asbestos or by covering it up so it cannot get into the
air. In addition, EPA provides guidance and support for reducing
asbestos exposure in other public buildings. Third, EPA regulates
the release of asbestos from factories and during building
demolition or renovation to prevent asbestos from getting
into the environment. The EPA also regulates the disposal
of waste asbestos materials or products, requiring these to
be placed only in approved locations. Fourth, EPA has proposed
a limit of 7 MFL (million fibers per liter), the concentration
of long fibers that may be present in drinking water. Fifth,
the Food and Drug Administration (FDA) regulates the use of
asbestos in the preparation of drugs and restricts the use
of asbestos in food-packaging materials.
The National Institute for Occupational Safety
and Health (NIOSH) has recommended that inhalation exposures
not exceed 0.1 f/cc. The Occupational Safety and Health Administration
(OSHA) has established an enforceable limit of 0.1 f/cc on
the average 8-hour daily concentration of asbestos allowed
in air in the workplace.
Does asbestos exposure cause health problems?
Health problems are usually related to the amount
and length of time of exposure to asbestos. After asbestos
fibers are inhaled they can easily enter and become trapped
in the airways and lung tissue and the body has difficulty
removing the fibers. Continued exposure to asbestos increases
the amount of asbestos that remains in the lungs. Diseases
related to asbestos may not show up until several years later.
It is known that asbestos causes cancer in people.
There are two types of cancer caused by exposure to high levels
of asbestos: cancer of the lung tissue itself and mesothelioma,
a cancer of the membrane that surrounds the lung and other
internal organs. Both of these are usually fatal. These
diseases don’t develop immediately, but show up only after
many years.
Interactions between cigarette smoke and asbestos
increase your chances of getting lung cancer. Studies of
workers suggest that breathing asbestos can increase the chances
of getting cancer in other parts of the body (stomach, intestines,
esophagus, pancreas, kidneys), but this is not certain.
People who are exposed to lower levels of asbestos may also have an increased
risk of developing cancer, but the risks are usually small
and are difficult to measure.
It is not known whether ingesting asbestos causes
cancer. Some people who had been exposed to asbestos fibers
in their drinking water had higher-than-average death rates
from cancer of the esophagus, stomach, and intestines. However,
it isn't known whether this was caused by asbestos or by something
else.
What illnesses are associated with asbestos exposure?
Asbestosis
Information on the health effects of asbestos
in people comes mostly from studies of people who were exposed
in the past to high levels of asbestos in the workplace.
Workers who breathe in asbestos may develop a slow buildup
of scar-like tissue in the lungs and in the membrane that
surrounds the lungs. This scar-like tissue does not expand
and contract like normal lung tissue and so breathing becomes
difficult. Blood flow to the lung may also be decreased and
this causes the heart to enlarge. This disease is called
asbestosis.
Asbestosis is a serious, progressive, long-term disease of the lungs. It is not cancer.
It is caused by inhaling asbestos fibers that irritate lung
tissues and cause the tissues to scar. The scarring makes
it hard for lungs to do their job of getting oxygen into the
blood. Symptoms of asbestosis include shortness of breath
and a dry crackling sound in the lungs while inhaling. The
chance of getting asbestosis is very small for those who do
not work with asbestos. Although there is no effective treatment
for asbestosis, symptoms of the disease can be managed under
the care of a physician. The disease, if severe, can cause
disability and death.
Lung Cancer
Lung cancer causes the
largest number of deaths related to asbestos exposure. People
who work in occupations involving the mining, milling, manufacturing,
and use of asbestos and its products are more likely to get
lung cancer than the general population. The most common
symptoms of lung cancer are coughing and a change in breathing.
Other symptoms include shortness of breath, persistent chest
pain, hoarseness, and anemia. People who develop these symptoms
do not necessarily have lung cancer, but should consult a
physician for advice. People who have been exposed to asbestos
and are also exposed to some other cancer-causing product,
such as cigarette smoke, have a greater risk of developing
lung cancer than people who have been exposed only to asbestos.
Mesothelioma
Asbestos workers have increased chances of getting
two types of cancer: cancer of the lung tissue itself and
mesothelioma, a cancer of the thin membrane that surrounds
the lung and other internal organs. Lung cancer is usually
fatal, while mesothelioma is invariably fatal within a few
months of diagnosis. These diseases do not develop immediately,
but appear only after a number of years.
Mesothelioma is a relatively rare form of cancer that is found in the thin lining (membrane)
of the lungs, chest, abdomen, and heart. Several hundred
cases are diagnosed each year in the United States, and most
cases are linked with exposure to asbestos. About 2 percent
of all miners and textile workers who work with asbestos,
and 10 percent of all workers who were involved in the manufacture
of gas masks containing asbestos, develop mesothelioma. This
disease may not show up until many years (generally 20 to
40 years or more) after asbestos exposure.
Is there a medical test to show whether I've been exposed
to asbestos?
Chest x-rays cannot show asbestos fibers, but
can find early signs of lung disease. Other tests, such as
lung function tests and high resolution CT scans, can also
detect changes in the lungs caused by asbestos. These changes
usually are not detectable until years after exposure.
Additional Information
The Consumer Product Safety Commission
(CPSC) is responsible for the regulation of asbestos in consumer
products. The CPSC maintains a toll-free information line
on the potential hazards of commercial products; the telephone
number is 1–800–638–2772. In addition, CPSC provides information
about laboratories for asbestos testing, guidelines for repairing
and removing asbestos, and general information about asbestos
in the home. Publications are available from the Office of
Public Affairs, Consumer Product Safety Commission, 4330 East-West
Highway, Bethesda, MD 20816; the telephone number is 301–504–0580.
The U.S. Food and Drug Administration is concerned with asbestos
contamination of foods, drugs, and cosmetics and will answer
questions on these topics. The address is Office of Consumer
Affairs, Food and Drug Administration, HFE–88, 5600 Fishers
Lane, Rockville, MD 20857; the telephone number is 301–443–3170.
Also, please check out these Internet links
for information regarding asbestos.
http://www.cdc.gov/niosh/asbestos.html
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