Asbestosis
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Asbestosis is a chronic inflammatory medical condition affecting the parenchymal tissue of the lungs. It occurs after long-term, heavy exposure to asbestos, e.g. in mining. Sufferers have severe dyspnea (shortness of breath) and are at an increased risk regarding several different types of lung cancer.
As clear explanations are not always stressed in non-technical literature, care should be taken to distinguish between several forms of relevant diseases. According to the World Health Organisation (WHO) (http://www.euro.who.int/document/aiq/6_2_asbestos.pdf), these may defined as; asbestosis (the subject of this article), lung cancer, and mesothelioma (generally a very rare form of cancer, when more widespread it is almost always associated with prolonged exposure to asbestos,).
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Signs and symptoms
The primary symptom of asbestosis is generally the slow, insidious onset of shortness of breath on exertion. In severe, advanced cases, this may lead to respiratory failure. Coughing is not usually a typical symptom, unless the patient has other, concomitant respiratory tract diseases.
People with extensive occupational exposure to the mining, manufacturing, handling or removal of asbestos are at risk of developing asbestosis. There is also an increased risk of lung cancer and mesothelioma. This risk is related to the total dose of asbestos received and the duration of asbestos exposure.
Diagnosis
The definitive diagnosis of asbestosis is largely dependent on a detailed and accurate clinical history. Reliable data on the level and duration of occupational exposure to asbestos is critical to the diagnosis (though, until recently, rarely available in practice). Histopathological diagnosis is usually not necessary for patient management but can be used to confirm the diagnosis, especially if the simultaneous presence of other diseases is suspected.
Pathogenesis
Asbestosis is the scarring of lung tissue resulting from the inhalation of asbestos fibers. When such fibers reach the alveoli (air sacs) in the lung, where oxygen is transferred into the blood, the foreign bodies (asbestos fibers) activate the lung's local immune system and provoke an inflammatory reaction. Macrophages phagocytose (ingest) the fibers and stimulate fibroblasts to deposit connective tissue. The result is fibrosis. The fibrotic scar tissue is much less efficient in gas exchange, reducing oxygen transfer to the blood, as well as the removal of carbon dioxide. The total lung capacity (TLC) may be reduced. In the more severe cases, the drastic reduction in lung function may induce heart failure (cor pulmonale).
Treatment
There is no curative treatment. Close monitoring (routine X-rays or even pleural biopsy) for mesothelioma is mandated. Oxygen therapy at home is often necessary to relieve the shortness of breath. Supportive treatment of symptoms includes respiratory treatments to remove secretions from the lungs by postural drainage, chest percussion, and vibration. Aerosol medications to thin secretions may be prescribed.
Legal issues
As asbestosis is often related to past employment, many workers have sought compensation from their previous employers for neglecting to implement safety measures rapidly after the link between asbestos, asbestosis and mesothelioma became known (some reports seem to place this as early as 1898 (http://en.wikipedia.org/wiki/Asbestos#Asbestosis_and_cancer)). Much controversy still exists, however, regarding such compensation, as discussed further in "Asbestos and the law".
External Links
- World Health Organization report (http://www.euro.who.int/document/aiq/6_2_asbestos.pdf)
- British Goverment Health and Safety Executive (http://www.hse.gov.uk/asbestos/index.htm)
- Asbestos Exposure - National Cancer Institute, USA (http://cis.nci.nih.gov/fact/3_21.htm)
- Public Health Guidance: Asbestos, Queensland Govt., Australia (http://www.health.qld.gov.au/phs/Documents/ehu/2691.pdf)
- Lungs Online - Asbestosis (http://www.lungsonline.com/asbestosis.html)da:Asbestose