What is asbestos?
Asbestos is a naturally occurring mineral that takes the form of hollow, microscopic fibers, which are nearly indestructible. It can be densely
packed into a tough, flexible and very useful material, which has been used for hundreds of years as an insulation, fireproofing and building
There are three major types of asbestos used in building and industry:
Chrysotile, or white asbestos - used as insulation, fireproofing and soundproofing.
Amosite, or brown asbestos - used in high friction applications like brake shoes and clutches.
Crocidolite, or blue asbestos - not as common as the other two, but the most toxic form.
About 95% of all asbestos used in the U.S. has been chrysotile, the least toxic form of asbestos.
Where is asbestos found?
Asbestos is often a component in the following materials:
Building ventilation systems
Vinyl floor tiles
Dry wall, dry wall tape and plaster
Roofing shingles, felt, tar and flashing
Decorative building materials
Sheathing on electronics and power cables
Automotive brake pads and clutches
Can asbestos be identified visually?
There is no way to visually identify asbestos. Many materials that contain asbestos look just the same as materials that don't. The only way to
confirm that a material is asbestos is to take samples and analyze the material in a laboratory. Therefore, it is best to treat anything that looks
like it may contain asbestos as if it does, until it is analyzed and proven to not contain any asbestos.
When is asbestos a potential health hazard?
Asbestos that is "friable" may be crumbled, pulverized or reduced to powder in your hand when dry. Friable asbestos has the potential to
release asbestos fibers that can become airborne, and potentially create a health hazard.
Asbestos that is bonded, coated, painted, covered, or otherwise protected so that it doesn't release airborne fibers, does not present a health
What are some health effects that could result from exposure to airborne asbestos fibers?
Asbestosis - a progressive, non-cancerous and irreversible scarring of the lungs that can produce shortness of breath. Typical latency period
is over 20 years.
Pleural disease - plaque deposits or a thickening of the thin tissue that separates the lungs from the other organs in the body.
Lung cancer - cancerous tumors that have a latency period of 20 to 30 years, usually fatal.
Mesothelioma - a cancer in the lining of the chest cavity or abdomen, very rare but always fatal. It is important to note that most asbestos
related diseases have occurred in workers who historically have had high exposures to asbestos. These exposures occurred in occupations
where asbestos was mined, milled,used in primary manufacturing and in insulation trades, such as shipbuilding. Before asbestos was
known to be a serious health hazard, exposure levels to airborne asbestos in these industries may have reached over 100 fibers/cc. This is
1000 times higher than the current Occupational Health and Safety Administration (OSHA) Permissible Exposure Limit (PEL) of 0.1 fibers/cc.
Workers whose only exposure to asbestos was in changing auto brake shoes containing asbestos have shown no increased incidence of
any asbestos related disease.
Research has shown that smoking significantly increases the risk of lung cancer in individuals who are exposed to unsafe levels of
Is there a medical test to determine whether I have been exposed to asbestos?
The most common test used to determine if you have received sustained exposure to asbestos is a chest x-ray. A chest x-ray is
recommended for detecting exposure to asbestos only in persons who have sustained relatively heavy exposure. A chest x-ray is of no value
for detecting evidence of asbestos exposure in a person whose exposure to asbestos has been only brief or transient. The x-ray cannot
detect the asbestos fibers themselves, but it can detect early signs of lung disease caused by asbestos. While other substances besides
asbestos can sometimes produce similar changes in the lungs, this test is usually reliable for detecting asbestos-related effects produced
by long-term exposures at relatively high concentrations of asbestos fibers. Other tests, such as gallium-67 lung scanning and
high-resolution computed tomography, are also useful in detecting changes in the lungs. However, there are currently no means of detecting
exposure-related effects from commonly encountered environmental exposures.
The most reliable test to determine if you have been exposed to asbestos is the detection of microscopic asbestos fibers in pieces of lung
tissue removed by surgery, but this is a very invasive test. A test can also be run to determine the presence of asbestos fibers in material
rinsed out of the lung. However, this test can cause some discomfort. Asbestos fibers can also be detected in mucus (sputum), urine, or
feces, but these tests are not reliable for determining how much asbestos may be in your lungs. Low levels of asbestos fibers are found in
these materials for nearly all people. Higher-than-average levels can show that you have been exposed to asbestos, but it is not yet possible
to use the results of this test to estimate how much asbestos you have been exposed to, or to predict whether you are likely to suffer any
health effects. Please see the toxicological profile for more information about how asbestos can be measured in people and in the
What can you do to limit your exposure to asbestos?
Most buildings, especially older ones, contain some amount of asbestos. But remember, asbestos is only a potential hazard if it is damaged
and friable, releasing fibers into the air we breathe.
If you come across something that appears to be friable asbestos, such as damaged insulation on a pipe, assume that it is asbestos, and
notify your supervisor. Do not damage or disturb the area. A sample of the material will be taken and analyzed. If it is determined to be
asbestos, it will either be removed or repaired so that it is protected and no longer releasing fibers.
If your job involves stripping or buffing floors that could be vinyl asbestos tile, this should be done infrequently, using a wet method. A soft,
non-abrasive pad should be used, and the machine should be run at low speed (below 300 rpm). Do not burnish or dry-buff flooring unless it
has sufficient finish so that the pad can't contact the bare floor.
***Source: Holland, John P., Asbestos, Hazardous Materials Toxicology - Clinical Principles of Environmental Health, Sullivan & Krieger, 1992. OEH&S 4/97
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