Asbestosis is a chronic, progressive inflammation of the lung caused by prolonged exposure to large quantities of asbestos, a naturally occurring material once widely used in construction, insulation, and manufacturing. Asbestosis can result in shortness of breath, coughing, and permanent lung damage.
Asbestos fibers can enter the air through weathering of natural deposits or from the breakdown of manufactured products containing asbestos. When asbestos is inhaled, fibers penetrate the breathing passages and irritate, inflame, and scar lung tissue. The scar tissue does not expand and contract normally, interferring with breathing and oxygen transfer. In advanced asbestosis, the lungs shrink, stiffen, and become honeycombed (riddled with tiny holes). The disease tends to progress, even after exposure to asbestos ceases.
Regulations, which were first introduced in the 1970s, have reduced use of asbestos in the United States. However, workers who handle automobile brake shoe linings, boiler insulation, ceiling acoustic tiles, electrical equipment, and fire-resistant materials may still be exposed to the substance. Asbestos is also 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.
Workers who were involved in mining, milling, manufacturing, installation or removal of asbestos products before the late 1970s are at the greatest risk of developing asbestosis. Examples of such occupations include:
The World Health Organization (WHO) estimated that about 125 million people in the world are exposed to asbestos in the workplace and that more than 107,000 people die each year from asbestos-related lung cancer, malignant mesothelioma and asbestosis resulting from occupational exposure. About 2 to 6 million people in the United States are estimated to have had significant levels of exposure. Although high exposures to asbestos ceased in the United States in the late 1970s, given that the latency period between initial exposure and development of asbestos-related diseases is 15 to 20 years or more, asbestosis remained an important public health problem. Between 1999 and 2013 there were 20,317 deaths due to asbestosis in the United States. According to a study by the Environmental Working Group, approximately 12,000–15,000 deaths per year in the United States are due to asbestos-related diseases, including malignant mesothelioma, asbestosis, lung cancer and gastrointestinal cancer.
If asbestos fibers are contained to prevent escape into the air, health risks are minimal. Occupational exposure is the most common cause of asbestosis, but the condition can also affect people who inhale asbestos fibers in their homes 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 or by washing clothes contaminated with asbestos fibers.
It is rare for asbestosis to develop in anyone who has not been exposed to large amounts of asbestos on a regular basis for at least ten 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).
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. Asbestosis can be difficult to diagnose because the symptoms can be similar to other respiratory diseases.
A battery of tests is used to diagnosis asbestosis. 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.
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, controlled coughing, and chest percussion and vibration can loosen bronchial secretions. The patient may require the use of supplemental oxygen by mask or by a plastic piece that fits into the nostrils. Sometimes prescription inhalers, which are used by persons with asthma, can aid in treatment. Severe cases of asbestosis may require that the patient have a lung transplant.
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.
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 develops the following symptoms:
The U.S. government has taken many steps to protect individuals from asbestos exposure:
Asbestosis cannot be cured, but its symptoms may be controlled. Doctors do not know why the health of some patients deteriorates and the condition of others remains the same, but many suspect the difference may be due to varying exposures of asbestos. People with asbestosis who smoke are at increased risk for developing lung cancer and are strongly advised to quit smoking. Other complications associated with asbestosis include chronic obstructive pulmonary disease (COPD), malignant mesothelioma, pleural effusion, and pleural plaques.
Persons can lower their exposure by being aware of sources of asbestos and avoiding those sources. In a home these sources may include damaged or deteriorating asbestos containing insulation or ceiling or floor tiles. The state or local health department should be contacted to learn how to test for asbestos and to aid in locating a company that can remove or contain the asbestos fibers.
If a person lives near asbestos mining or processing sites, exposure can be reduced by frequent hand and face washing, regular cleaning of the home of dust, use of door mats, and removal of shoes when entering the home. Federal laws regulate work practices to limit the amount of asbestos being brought home. These practices may include workers' showering and changing clothes before leaving work, storing street clothes in a separate area of the workplace, and laundering work clothes at work.
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.
People 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. Persons at risk of developing asbestosis should also do the following:
See also Asbestos .
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Dodson, Ronald F., and Samuel P. Hammar, eds. Asbestos: Risk Assessment, Epidemiology, and Health Effects, Second Edition. Boca Raton, FL: CRC Press, 2011.
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U.S. National Library of Medicine. “Asbestosis.” // http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0023537/ (accessed May 31, 2018).
American Lung Association, 1301 Pennsylvania Ave. NW, Ste. 800, Washington, DC, 20001, (202) 758-3355, Fax: (202) 452-1805, (800) 548-8252, email@example.com, http://www.lungusa.org .
Judith L. Sims