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Asbestosis

Definition

Asbestos is the name of a group of minerals that are made up of bundles of tiny fibers composed of hydrated magnesium silicates. It is mined from the ground. Asbestos has been widely used in building and manufacturing industries because it is not affected by heat or chemicals.
Asbestosis is a lung condition caused by breathing in asbestos fibers. Usually, when particles in the air are breathed in, they are filtered out by the nose or the upper airways of the lungs. But asbestos particles are very thin and light, and sometimes are not filtered out before they reach the lungs. After years of exposure, asbestos can damage lung tissue and is responsible for causing several serious diseases, including cancer .

Causes

Asbestosis is caused when the fibers are inhaled deep into the lungs. Here they are trapped in tiny airways where they cause scarring, called fibrosis, to the lung tissue. Repeated or continuous exposure over a long time can cause scarring over large areas of the lungs. When this happens, lungs lose their elasticity. When lungs can’t expand and contract normally, a person will experience shortness of breath. Scarring also decreases the ability of the lungs to do their work of exchanging oxygen and carbon dioxide.
Thickening and Fibrosis of Lung Tissue
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Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Asbestosis primarily affects people who are regularly exposed to asbestos. The more a person is exposed, the greater the risk of developing an asbestos-related disease. However, most people who have had prolonged exposure to asbestos do not develop asbestosis. Those at highest risk are:
  • People who handle asbestos material at their workplace:
    • Workers who mine or process asbestos
    • Construction workers
    • Shipyard workers
    • Vehicle mechanics
  • Family members of people who work with asbestos and bring the fibers home on their hair or clothing
  • People who work at sites where asbestos is found
  • Smoking

Symptoms

Asbestosis takes a long time to develop. The earliest symptoms usually show up 10-40 years after first exposure. The disease can develop even when exposure to asbestos ended years before. The severity of the disease depends on the amount and length of time of exposure to asbestos. Symptoms get worse as the disease progresses and may include:
  • Shortness of breath—this is the first noticeable symptom and occurs with exercise or heavy effort
  • Cough—the cough is persistent and nonproductive (which means no mucus is produced)
Other symptoms may include:
  • Chest pain or tightness
  • Feeling generally unwell
  • Loss of appetite
  • Finger clubbing, in some cases, caused by a build-up of fluid
  • Weight loss

Diagnosis

The diagnosis is made based on:
  • Reliable history of exposure to asbestos
  • Evidence of lung scarring and fibrosis which is based on a physical exam and/or additional tests
  • Absence of other causes that may produce similar clinical pictures
Tests used in diagnosis of asbestosis:
  • Chest X-ray—changes seen on the exam usually have a distinctive pattern
  • CT scan —a type of x-ray that uses a computer to make pictures of structures inside the body. A high resolution CT is more sensitive that a plain x-ray in detecting abnormalities in individuals who were exposed to asbestos.
  • Pulmonary function test—a test that measures how well the lungs take in and exhale air. The test can show if the lungs have reduced ability to function properly.
  • Oximetry is a noninvasive means to assess oxygen status.

Treatment

There is no treatment to cure asbestosis, and the disease slowly worsens. The first and most important changes a person can make are the following:
  • Prevent further exposure to asbestos
  • Stop smoking; people who have asbestosis and smoke cigarettes greatly increase their risk of developing lung cancer
Once the condition is diagnosed, treatment involves keeping the patient healthy and treating the symptoms. These measures include:
  • Getting immediate treatment for colds and other respiratory infections
  • Staying updated with vaccinations, especially for flu (influenza) and pneumococcus
  • Avoiding crowds, where infections might be spread
  • Having regular chest x-rays to watch for signs of cancers associated with asbestos
  • Having oxygen therapy and other respiratory therapies that can make breathing easier
  • Improve the nutritional state
  • Encourage breathing and physical exercises
  • Home oxygen, if necessary

Prevention

Since the 1970s, asbestos use and handling has been increasingly controlled by the government. Asbestosis can be prevented by controlling the asbestos dust and fibers in the workplace. In addition, people who handle asbestos at work must shower and change their clothes before leaving work. As a result of these measures, fewer people develop the disease.
People who need to have asbestos removed from their house should seek help from professionals trained in asbestos removal.
It is also important to note that smoking increases the attack and/or progression rate of asbestosis.

RESOURCES

Agency for Toxic Substances and Disease Registry (ATSDR) http://www.atsdr.cdc.gov

American Cancer Society http://www.cancer.org

Mine Safety and Health Administration US Department of Labor http://www.msha.gov

National Cancer Institute http://www.cancer.gov/

National Institute for Occupational Safety Centers for Disease Control and Prevention http://www.cdc.gov/niosh

Occupational Safety and Health Administration (OSHA) US Department of Labor http://www.osha.gov

US Environmental Protection Agency http://www.epa.gov/asbestos

CANADIAN RESOURCES

Canadian Centre for Occupational Health and Safety (CCOHS) http://www.ccohs.ca

The Lung Association http://www.lung.ca

References

Asbestos exposure: questions and answers. Cancer Information Service, National Cancer Institute website. Available at: http://www.cancer.gov/cancertopics/factsheet/Risk/asbestos . Accessed December 13, 2006.

Asbestos exposure: questions and answers. Cancer Information Service, National Cancer Institute website. Available at: http://cis.nci.nih.gov/fact/3%5F21.htm . Accessed August 4, 2005.

Asbestos: health effects of exposure to asbestos. Agency for Toxic Substances and Disease Registry (ATSDR) website. Available at: http://www.atsdr.cdc.gov/asbestos/asbestos/health%5Feffects/ . Accessed December 13, 2006.

Asbestos: health effects of exposure to asbestos. Agency for Toxic Substances and Disease Registry (ATSDR) website. Available at: www.atsdr.cdc.gov/asbestos/asbestos%5Feffects.html. Accessed August 4, 2005.

Becklake MR, Bagatin E, Neder JA: Asbestose-related diseases of the lungs and pleura: uses, trends and management over the last century. Int J Tuberc Lung Dis 2007;11:356-69.

Beers MH, Fletcher AJ, Jones TV, et al. The Merck Manual of Medical Information: Second Home Edition . Whitehouse Station, NJ: Merck Research Laboratories; 2003.

Diagnosis and initial management of nonmalignant diseases related to asbestos. Am J Respir Crit Care Med. 2004; 170:691

Mossman BT, Gee JBL. Medical progress: Asbestos-related diseases. N Engl J Med. 1989;320:1721.

O’Reilly KM, Mclaughlin AM, Beckett WS, Sime PJ: Asbestos-related lung disease. Am Fam Physician 2007;75:683-8.

Sette A, Neder JA, Nery LE, et al. Thin-section CT abnormalities and pulmonary gas exchange impairment in workers exposed to asbestos. Radiology. 2004; 232:66.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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