Asbestosis is a serious lung disease that occurs when asbestos fibers are inhaled and become lodged in the inner layers of the lungs. Asbestosis is not a type of cancer, but malignant mesothelioma is; when malignant mesothelioma occurs in the lungs, it is called pleural mesothelioma. Some patients do acquire asbestosis and then develop pleural mesothelioma.
Asbestosis develops over time as the asbestos fibers begin to cause inflammation in the lungs and the development of fibrosis, or scar tissue. The diagnosis of asbestosis occurs when the scar tissue becomes large enough to be identified on an x-ray. As the scar tissue expands throughout the lungs, the lungs become increasingly dysfunctional and breathing becomes labored. Asbestosis can lead to disability and death.
The lungs are the place in the body where air comes in direct contact with blood cells. In order to ensure an efficient transfer of oxygen from the air into the blood, the innermost layers of the lungs must be kept highly sterile. The sterilization of air occurs through a matrix of filtration systems, starting with the nose and the other air passages leading into the lungs. The reason asbestos is hazardous is because asbestos particles are able to bypass the lungs' filtration systems and become imbedded in the innermost layers of the lungs.
Asbestos particles are long, extremely thin, microscopic fibers. When asbestos is in the air, these particles are inhaled by those in close proximity. The fibers are so thin and light that they cannot be properly filtered by the lungs.The asbestos can become embedded in various parts of the lungs, including the interstitium (the area surrounding the alveoli).
Once embedded, the asbestos particles are attacked by the body's immune system. The immune system releases digestive molecules called macrophages, which target and devour foreign objects in the body. Unfortunately, because asbestos is a hard, fibrous mineral, the macrophages are unable to eliminate them from the lungs. As the macrophages attempt to wipe out the asbestos, they create scar tissue in the area where the asbestos is embedded. But since the macrophages are unable to remove the asbestos, the body’s immune system sends more and more macrophages, creating more scar tissue. This creates a chain reaction that cannot be stopped. People who are exposed to airborne asbestos particles inhale hundreds or thousands of asbestos fibers, which means that hundreds or thousands of these chain reactions occur, all of which create scar tissue.
When scar tissue in the interstitium becomes advanced and there is large-scale injury to tissue in this area of the lung, this is called fibrosis; or, more specifically, interstitial fibrosis, lung fibrosis or asbestosis.
The first onset of asbestosis symptoms sometimes takes place years after asbestos exposure. Manifestations of asbestosis rarely occur less than 10 years following first exposure and are more common after 20 years or more. Anyone who has come in contact with asbestos is at risk for developing asbestosis, not just the workers who directly handled the fibers.
The most common symptom of asbestosis is shortness of breath. In fact, asbestosis has been called a monosymptomatic disease because shortness of breath is consistently reported and is the most distressing symptom. Breathing occurs with heavy effort and becomes more difficult as the disease progresses. Asbestosis is also associated with persistent and productive cough, and sometimes with distressing spasms. Chest tightening, chest pain, ill feeling, fitful sleep and appetite loss have also been associated with asbestosis, but not as commonly as shortness of breath.
The fibrosis associated with asbestosis is normally detected with an X-ray. There is no treatment for asbestosis, and once symptoms appear, they rarely subside. A patient’s prognosis depends upon several factors, including the type of asbestos fiber the patient is exposed to, the level and duration of exposure to asbestos and (sometimes) the status of the X-ray at the time of detection. Progression continues even without additional exposure and is thought to accelerate with additional exposure.
Shortness of breath becomes more and more pronounced as the disease progresses. The end result is failure of the lungs and eventual heart failure resulting from the stress placed on the heart. Most patients do not die of asbestosis, but perish due to other ailments of the lungs brought about by asbestosis, such as mesothelioma and other lung cancers.
[Page updated August 2009]