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Health Effects of Exposure to Asbestos
Significant exposure to any type of asbestos
will increase the risk of lung cancer,
mesothelioma and nonmalignant lung
and pleural disorders, including asbestosis,
pleural plaques, pleural thickening, and pleural effusions. This
conclusion is based on observations of these diseases in groups of
workers with cumulative exposures ranging from about 5 to 1,200
fiber-year/mL. Such exposures would result from 40 years of
occupational exposure to air concentrations of 0.125 to 30 fiber/mL.
See Detecting
Asbestos for typical levels of concentration. The
conclusion is supported by results from animal and mechanistic
studies.
| Diseases from asbestos exposure take a long time to develop.
Most cases of lung cancer or asbestosis in asbestos workers
occur 15 or more years after initial exposure to asbestos.
Tobacco smokers who have been exposed to asbestos have a
"far greater-than-additive" risk for lung cancer than do
nonsmokers who have been exposed, meaning the risk is
greater than the individual risks from asbestos and smoking
added together. The time between diagnosis of mesothelioma and
the time of initial occupational exposure to asbestos commonly
has been 30 years or more. Cases of mesotheliomas have been
reported after household exposure of family members of
asbestos workers and in individuals without occupational
exposure who live close to asbestos mines.
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Asbestos fibers lodged in the lungs. Asbestos-related conditions affect the lungs and surrounding tissues |
Asbestos Facts:
- When asbestos fibers are inhaled, most fibers are expelled, but some can become lodged in the lungs and remain there throughout life. Fibers can accumulate and cause scarring and inflammation. Enough scarring and inflammation can affect breathing, leading to disease.
- People are more likely to experience asbestos-related disorders when they are exposed to high concentrations of asbestos, are exposed for longer periods of time, and/or are exposed more often.
- Inhaling longer, more durable asbestos fibers (such as tremolite and other amphiboles) contributes to the severity of asbestos-related disorders.
- Exposure to asbestos, including tremolite, can increase the likelihood of lung cancer, mesothelioma, and non-malignant lung conditions such as asbestosis (restricted use of the lungs due to retained asbestos fibers) and changes in the lung lining.
- Changes in the lining of the lungs (pleura) such as thickening, plaques, calcification, and fluid around the lungs (pleural effusion) may be early signs of asbestos exposure. These changes
can affect breathing more than previously thought.
Pleural effusion can be an early warning sign for mesothelioma (cancer of the lining of the lungs).
- Most cases of asbestosis or lung cancer in workers occurred 15 years or more after the person was first exposed to asbestos.
- Most cases of mesothelioma are diagnosed 30 years or more after the first exposure to asbestos.
- Mesothelioma has been diagnosed in asbestos workers, family members, and residents who live close to asbestos mines.
- Health effects from asbestos exposure may continue to progress even after exposure is stopped.
- Smoking or cigarette smoke, together with exposure to asbestos, greatly increases the likelihood of lung cancer.
Health Risks of Asbestos Exposure
Chronic exposure to asbestos may increase the risk of lung cancer, mesothelioma, and nonmalignant lung and pleural disorders. Evidence in humans comes from epidemiologic studies
as well as numerous studies of workers exposed to asbestos in a
variety of occupational settings. Tremolite asbestos exposure has
been associated with an increased incidence of disease in
vermiculite miners and millers from Libby, Montana. This evidence is supported by reports of increased incidences of nonmalignant respiratory diseases, lung cancer, and mesothelioma in villages in various regions of the world that have traditionally used tremolite-asbestos whitewashes in homes or have high surface deposits of tremolite asbestos and by results from animal studies.
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Risk Factors
Various factors determine how exposure to asbestos affects an
individual:
- Exposure concentration - what was the concentration of
asbestos fibers?
- Exposure duration - how long did the exposure
time period last?
- Exposure frequency - how often during that
time period was the person exposed?
- Size, shape and chemical makeup
of asbestos fibers:
Long and thin fibers are expected to reach the
lower airways and alveolar regions of the lung, to be retained in
the lung longer, and to be more toxic than short and wide fibers or
particles. Wide particles are expected to be deposited in the upper
respiratory tract and not to reach the lung and pleura, the sites of
asbestos-induced toxicity. Short, thin fibers, however, may also
play a role in asbestos pathogenesis. Fibers of amphibole
asbestos such as tremolite asbestos, actinolite asbestos, and
crocidolite asbestos are retained longer in the lower respiratory
tract than chrysotile fibers of similar dimension.
- Individual risk factors, such as a person's history of
tobacco use (smoking) and other pre-existing lung disease,
etc.
Note, cigarette smoke and asbestos together significantly
increase your chances of getting lung cancer. Therefore, if you have
been exposed to asbestos you should stop smoking. This may be the
most important action that you can take to improve your health and
decrease your risk of cancer.
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| Asbestosis is a serious,
progressive, long-term disease of the lungs. Asbestosis is not
a cancer. Inhaling asbestos fibers that
irritate and inflame lung tissues, causing the lung tissues to
scar, causes asbestosis. The scarring makes it hard to breathe
and difficult for oxygen and carbon dioxide pass through the
lungs. Asbestosis generally progresses slowly. The
latency period for the onset of asbestosis is typically 10-20
years after the initial exposure. The disease can vary from
asymptomatic (no symptoms) to disabling and potentially fatal. |
Microscopic view of lung tissue with
asbestosis.
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Signs and Symptoms of asbestosis can include:
- Shortness of breath is the primary symptom
- A persistent and productive cough (a cough that expels mucus)
- Chest tightness
- Chest pain
- Loss of appetite
- A dry, crackling sound in the lungs while inhaling.
Persons with significant exposure to asbestos are at risk for
developing various types of pleural (lining of the lungs)
abnormalities. These abnormalities include
pleural plaques, pleural thickening, pleural calcification, and pleural
mesothelioma.
Mesothelioma is a rare cancer which may affect the lining of the
lings (plura) or the abdominal contents (peritoneum). Most mesotheliomas are
caused by exposure to asbestos.
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Scanning Electron Micrograph of Lung
Cancer Cells.
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Lung cancer is a malignant tumor that
invades and obstructs the lung's air passages. Cigarette
smoking greatly increases the likelihood of a person
developing lung cancer as the result of asbestos exposure. The
most common symptoms of lung cancer are cough, wheezing,
unexplained weight loss, coughing up blood, and
labored breathing. Other symptoms of lung cancer include
shortness of breath, persistent chest pain, hoarseness, and
anemia. People who develop these symptoms do not necessarily
have lung cancer, but they should consult a physician for
advice. |
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