Asbestosis

Definition

Asbestosis is chronic, progressive inflammation of the lung. It is not contagious.

Description

Asbestosis is a consequence of prolonged exposure to large quantities of asbestos, a material once widely used in construction, insulation, and manufacturing. When asbestos is inhaled, fibers penetrate the breathing passages and irritate, fill, inflame, and scar lung tissue. In advanced asbestosis, , the lungs shrink, stiffen, and become honeycombed (riddled with tiny holes).

Legislation has reduced use of asbestos in the United States, but workers who handle automobile brake shoe linings, boiler insulation, ceiling acoustic tiles, electrical equipment, and fire-resistant materials are still exposed to the substance. Asbestos is used in the production of paints and plastics. Significant amounts can be released into the atmosphere when old buildings or boats are razed or remodeled.

Asbestosis is most common in men over 40 who have worked in asbestos-related occupations. Smokers or heavy drinkers have the greatest risk of developing this disease. Between 1968 and 1992, more than 10,000 Americans over the age of 15 died as a result of asbestosis. Nearly 25% of those who died lived in California or New Jersey, and most of them had worked in the construction or shipbuilding trades.

Causes & symptoms

Occupational exposure is the most common cause of asbestosis, but the condition also strikes people who inhale asbestos fiber or who are exposed to waste products from plants near their homes. Family members can develop the disease as a result of inhaling particles of asbestos dust that cling to workers' clothes.

It is rare for asbestosis to develop in anyone who hasn't been exposed to large amounts of asbestos on a regular basis for at least 10 years. Symptoms of the disease do not usually appear until 15-20 years after initial exposure to asbestos.

The first symptom of asbestosis is usually shortness of breath following exercise or other physical activity. The early stages of the disease are also characterized by a dry cough and a generalized feeling of illness.

As the disease progresses and lung damage increases, shortness of breath occurs even when the patient is at rest. Recurrent respiratory infections and coughing up blood are common. So is swelling of the feet, ankles, or hands. Other symptoms of advanced asbestosis include chest pain, hoarseness, and restless sleep. Patients who have asbestosis often have clubbed (widened and thickened) fingers. Other potential complications include heart failure, collapsed (deflated) lung, and pleurisy (inflammation of the membrane that protects the lung).

Diagnosis

Screening of at-risk workers can reveal lung inflammation and lesions characteristic of asbestosis. Patients' medical histories can identify occupations, hobbies, or other situations likely to involve exposure to asbestos fibers.

X rays can show shadows or spots on the lungs or an indistinct or shaggy outline of the heart that suggests the presence of asbestosis. Blood tests are used to measure concentrations of oxygen and carbon dioxide. Pulmonary function tests can be used to assess a patient's ability to inhale and exhale, and a computed tomography scan (CT) of the lungs can show flat, raised patches associated with advanced asbestosis.

Treatment

The goal of treatment is to help patients breathe more easily, prevent colds and other respiratory infections, and control complications associated with advanced disease. Ultrasonic, cool-mist humidifiers or controlled coughing can loosen bronchial secretions.

Regular exercise helps maintain and improve lung capacity. Although temporary bed rest may be recommended, patients are encouraged to resume their regular activities as soon as they can.

Antibiotics may be prescribed to combat infection. Aspirin or acetominophen (Tylenol) can relieve minor discomfort and bronchodilators that are swallowed or inhaled can relax and widen breathing passages.

Diuretics (drugs that increase urine production and excretion) or digitalis glycoside (Digitalis purpurea) are prescribed for some patients. Others may need to use supplemental oxygen or use less salt.

Anyone who develops symptoms of asbestosis should see a family physician or lung disease specialist. A doctor should be notified if someone who has been diagnosed with asbestosis:

• Coughs up blood
• Continues to lose weight
• Is short of breath
• Has chest pain
• Develops a sudden fever of 101°F (38.3°C) or higher
• Develops unfamiliar, unexplained symptoms.

Prognosis

Asbestosis can't be cured, but its symptoms can be controlled. Doctors don't know why the health of some patients deteriorates and the condition of others remain the same, but believe the difference may be due to varying exposures of asbestos. People with asbestosis who smoke, particularly those who smoke more than one pack of cigarettes each day, are at increased risk for developing lung cancer and should be strongly advised to quit smoking.

Prevention

Workers in asbestosis-related industries should have regular x rays to determine whether their lungs are healthy. A person whose lung x ray shows a shadow should eliminate asbestos exposure even if no symptoms of the condition have appeared.

Anyone who works with asbestos should wear a protective mask or a hood with a clean-air supply and obey recommended procedures to control asbestos dust. Anyone who is at risk of developing asbestosis should:

• Not smoke
• Be vaccinated against influenza and pneumonia
• Exercise regularly to maintain cardiopulmonary fitness
• Avoid crowds and people who have respiratory infections.

A person who has asbestosis should exercise regularly, relax, and conserve energy whenever necessary.

Key Terms

Asbestos

A silicate (containing silica) mineral that occurs in a variety of forms; it is characterized by a fibrous structure and resistance to fire.

Further Reading

For Your Information

Books

• Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Medicine. 20th ed. Philadelphia: W.B. Saunders. 1996.
• Burton, George G., John E. Hodgkin, and Jeffrey J. Ward, eds. Respiratory Care: A Guide to Clinical Practice. 4th ed. Philadelphia: Lippincott, 1997.
• Farzan, Sattar. A Concise Handbook of Respiratory Diseases. 4th ed. Stamford, CT: Appleton & Lange, 1997.

  Organizations

• American Lung Association. 1740 Broadway, New York, NY 10079-4374. (800) LUNGUSA. http://www.lungusa.org/

  Other

• Asbestosis. http://www.thriveonline.com/health/Library/illsymp/illness31.html (1 May 1998)
• 1996 World Report: Asbestosis Mortality. http://www.cdc.gov/hiosh/w7asbt9.html (1 May 1998).

Gale Encyclopedia of Medicine. Gale Research, 1999.