Is there a medical test to
determine whether I have been
exposed to asbestos?
The most common test used to determine if you have
been exposed to asbestos is a chest X ray. The X ray
cannot detect the asbestos fibers themselves, but can
detect early signs of lung disease caused by asbestos.
While other things besides asbestos can sometimes
produce similar changes in the lungs, this test is usually
reliable for detecting asbestos-related effects.
It is also possible to test for the presence of asbestos
fibers in urine, feces, mucus, or material rinsed out of
the lung by a doctor. 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 to estimate how much asbestos you have been
exposed to, or to predict whether you are likely to suffer
any health effects.
Despite the ongoing debate concerning health
effects resulting from the different asbestos fiber types,
Agency for Toxic Substances and Disease Registry
(ATSDR) considers the different mineral forms of
asbestos to be known, human cancer-causing
substances with a prolonged latency period of between
10 and 30 years between exposure and the onset of
disease.
Where can I get more
information?
If you have any more questions or concerns not
covered here, please contact your state health or
environmental department or:
Agency for Toxic Substances and
Disease Registry
Division of Toxicology
1600 Clifton Road, E-29
Atlanta, Georgia 30333
This agency can also give you information on the
location of the nearest occupational and environmental
health clinics in your area. Such clinics specialize in
recognizing, evaluating, and treating illnesses that result
from exposure to hazardous substances, such as
asbestos.
EPA910-F-98-002
United States Region 10
Environmental Protection 1200 Sixth Avenue
Agency Seattle WA 98101-1128
Asbestos
And Your Health
A photograph of asbestos fibers
(magnified by an electron microscope).
Condensed from
"ATSDR Public Health Statement,
December 1990"
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What is asbestos?
Asbestos is the name applied to a group of six
different minerals (amosite, chrysotile, tremolite,
actinolite, anthophyllite, and crocidolite) that occur
naturally in the environment. The most common mineral
type is white (chrysotile), but others may be blue
(crocidolite), gray (anthophyllite), or brown (amosite).
These minerals are made up of long, thin fibers that
appear somewhat similar to fiberglass. Asbestos fibers
are very strong and are resistant to heat and chemicals.
Because of these properties, asbestos fibers have been
used in a wide range of products, mostly in building
materials, friction products, and heat-resistant fabrics.
Because the fibers are so resistant to chemicals,
they are also very stable in the environment; they do
not evaporate into air or dissolve in water, and they are
not broken down over time.
How might I be exposed to
asbestos?
You are most likely to be exposed to asbestos by
breathing in tiny asbestos fibers suspended in the air.
These fibers can come from natural outcroppings of
asbestos, but many come from the degradation or
breakdown of man-made products such as insulation,
ceiling and floor tiles, roof shingles, cement, automotive
brakes and clutches, and many other products.
In indoor air, the concentration of asbestos depends
on whether asbestos was used for insulation, ceiling or
floor tiles, or other purposes, and whether these
asbestos-containing materials are in good condition or
are deteriorated and easily crumbled. People who work
with asbestos (e.g., miners, insulation workers,
automobile brake mechanics) are likely to be exposed
to much higher levels of asbestos particles in air than
people who work, live, or attend school in buildings
containing asbestos products. You can also be exposed
to asbestos by drinking fibers present in water. Even
though asbestos does not dissolve in water, fibers can
enter water by being eroded from natural deposits or
piles of waste asbestos, or from cement pipes used to
carry drinking water.
How can asbestos enter and
leave my body?
If you breathe asbestos fibers into your lungs, some
of the fibers will be deposited in the air passages and
on the cells that make up your lungs. However, very few
of these fibers move through your lungs into your body.
Instead, most fibers are removed from your lungs by
being carried away in a layer of mucus to the throat,
where they are swallowed into the stomach. This usually
takes place within a few hours of exposure, but fibers
that are deposited in the deepest parts of the lung are
removed more slowly, and some can remain in place for
many years and may never be removed.
If you swallow asbestos fibers (either those present
in water or those that are moved to your throat from
your lungs), nearly all the fibers pass along your
intestines within a few days and are excreted in the feces.
A small number of fibers become stuck in the cells that
line your stomach or intestines, and a few penetrate the
lining and get into the blood. Some of these become
trapped in other tissues, and some are removed in the
urine.
How can asbestos affect my
health?
The U.S. Department of Health and Human Services
has determined that asbestos is a known carcinogen,
that is, causes cancer in humans. Asbestos fibers can
have serious effects on your health if inhaled. There is
no known safe exposure to asbestos. The greater the
exposure, the greater the risk of developing an asbestos-
related disease. Information on the health effects of
asbestos in humans comes mostly from studies of
people who were exposed in the past to high levels of
asbestos in the workplace. These asbestos workers were
found to 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. Both lung
cancer and mesothelioma are usually fatal. The amount
of time between exposure to asbestos and the first signs
of disease can be as much as 30 years. It is known that
smokers exposed to asbestos have a much greater
chance of developing lung cancer than just from smoking
alone.
These diseases do not appear immediately, but
develop only after around 20 years. There is also some
evidence from studies of workers that breathing asbestos
can increase the chances of getting cancer in other
locations (e.g..stomach, intestines, esophagus,
pancreas, kidneys), but this is less certain. Members of
the public who are exposed to lower levels of asbestos
may also have increased chances of getting cancer, but
the risks are usually small and are difficult to measure
directly.
Besides causing cancer, breathing asbestos can
also cause a slow accumulation of scar-like tissue in
the lungs and in the membrane which 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. When the injury is
mostly in the lung itself, the disease is called asbestosis.
This is a serious disease, and can eventually lead to
disability or death in people exposed to high levels of
asbestos. However, asbestosis is not usually of concern
to people exposed to low levels of asbestos. Similar
injury to the membrane surrounding the lung is quite
common in people exposed to asbestos, but effects on
breathing are usually not serious.
The health effects from swallowing asbestos are
unclear. Some groups of people who have been exposed
to asbestos fibers in their drinking water have higher-
than-average death rates from cancer of the esophagus,
stomach, and intestines. However, it is very difficult to
tell whether this is caused by asbestos or by something
else. Where asbestos fibers penetrate the skin, asbestos
warts (which are non-malignant) may result.
What levels of exposure have
resulted in harmful health effects?
No "safe" exposure threshold (with respect to for
inhaling asbestos fibers) has been established, but the
risk of disease generally increases with the length and
amount of exposure. Another key factor which increases
the risk of asbestos-related diseases is smoking
cigarettes.
As noted above, eating or drinking asbestos fibers
may increase risk of cancer, but this is not certain. Eating
or drinking asbestos fibers is not thought to cause any
harmful noncancer effects.
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