Asbestosis (011)

The facts

Asbestosis is a harmful lung condition that develops in people who have inhaled asbestos dust. When someone inhales the dust, the microscopic asbestos fibres settle in the lungs, where they may cause permanent lung damage as well as chronic breathing symptoms.

One of the unusual things about asbestosis is the long "lag-time" between asbestos exposure and the resulting illness. For example, a year of exposure in youth may not cause symptoms until 30 years later.

Once someone develops asbestosis, there is no cure. Breathing problems will get steadily worse, and in about 15% of people, severe shortness of breath and respiratory failure develop. For someone who smokes and has had asbestos exposure, there is a greatly increased chance of developing lung cancer. Symptoms may appear within 10 years of the initial exposure.

Lung transplantation is the only way to manage end-stage asbestos lung disease, and most people who need it are not eligible candidates because of their advanced age or due to other medical problems.

Causes

Asbestosis is what doctors call an occupational lung disease, caused by inhaling harmful particles while at work. Diseases due to chronic inhalation of mineral dusts are called pneumoconiosis. The kind of lung disease or pneumoconiosis that develops depends on the size and kind of particles someone keeps breathing in. Fortunately, the body is able to get rid of most inhaled particles. Special cells in the lungs engulf them and make them harmless. But some particles like asbestos cause damage that can't be reversed.

Asbestos is the term for a group of minerals used in many industries. They are categorized based on their shape. Long, straight, rod-like asbestos fibres seem to be a greater health hazard than long, curly fibres. When inhaled into the lungs, asbestos fibres cause scars (pulmonary fibrosis) and may restrict lung movements (restrictive lung disease). Breathing in asbestos can also cause the two membranes covering your lungs (the pleura) to thicken.

The more you are exposed to asbestos fibres, the greater your risk of developing asbestosis or other asbestos-related conditions. You can be at risk for asbestos exposure if you work as a janitor, welder, electrician, plumber, construction worker, carpenter, boilermaker, insulation installer, shipbuilder, miner, or railway worker, or if you're involved in textile manufacturing. Construction work; demolition; renovation; and jobs that require the cutting, filing, sanding, or scraping of asbestos-containing materials may put you at a high risk.

Symptoms and Complications

If you experience symptoms of asbestosis, this may well mean that many scars have formed in your lungs. The lungs lose their elasticity or ability to fill up properly with oxygen. Thus, the first symptoms are shortness of breath and increased breathlessness when exercising.

Worsening in your breathing occurs as asbestosis progresses. Cough, sputum production, and wheezing are less common and are generally associated with smoking. You may display what is known as clubbing of the fingertips (they thicken and enlarge), or develop a blue colour under your nails and a bluish tinge around your mouth.

Even brief exposure to asbestos at some time in the past will dramatically increase the risk of developing lung cancer and malignant mesothelioma (a rare, fatal cancer of the lining of organs such as the lungs, abdomen, and chest).

Some research has also shown that asbestos causes an increased risk of developing cancers of the esophagus, stomach, intestines, and rectum. This may be related to the swallowing of asbestos fibres that were inhaled and then coughed up from the lungs. If you are a smoker who has been exposed to asbestos over the long term, your likelihood of developing lung cancer is greatly increased, especially if you smoke more than one pack of cigarettes a day. It appears that there is a "dose-response relationship" between asbestos exposure, smoking, and lung cancer: the greater the exposure to both asbestos and cigarette smoke, the higher the risk of cancer.

Making the Diagnosis

If you suffer from a cough and habitual shortness of breath, you should tell a doctor about any possible exposure to asbestos. Your doctor will also probably talk to you about your work history to determine this. Because asbestosis has no symptoms that are completely unique, diagnosis is usually made after excluding alternative diagnoses and considering symptoms alongside a confirmed history of asbestos exposure.

Only when there is clear evidence of asbestosis will a doctor assume that asbestos exposure played a role. This is because showing a cause-and-effect relationship to work-related asbestos exposure presents many medical and legal problems, especially if you are a smoker. Chest X-rays or a CT scan will confirm whether the lungs are scarred. Pulmonary (or lung) function tests may reveal that lung function is decreased. In rare cases, a lung biopsy can be done to actually show the asbestos fibres in the lungs, but this seldom changes the management of asbestosis.

Treatment and Prevention

There is currently no specific treatment for asbestosis. Supportive care is used to treat symptoms of asbestosis. The management of asbestosis should focus on preventive measures.

Asbestosis is preventable, mainly through reducing the amount of asbestos dust in the workplace. As many industries are phasing out the use of asbestos because of its health hazards, the number of people who have asbestosis is now decreasing. However, there is still poor control over the use of asbestos in developing countries, and immigrants may continue to present with the disease for many years.

If you have asbestosis, you must immediately stop all exposure to asbestos. If you're a smoker, you must also stop smoking in order to prevent serious complications. There are no specific treatments available for asbestosis. General treatments available for the kind of restrictive lung disease it causes include bronchodilator inhalers and exercise programs. Respiratory infections should be treated promptly. If you have asbestosis, vaccination shots against pneumococcal pneumonia and the flu can help prevent lung infection. Therapy with pure oxygen helps if you have an advanced case of the illness.

If you work in an industry that uses asbestos, you should make sure your employer takes preventive steps to ensure your safety and that of your fellow workers. Many countries have adopted regulations about acceptable limits of asbestos exposure and use mandatory guidelines to carefully monitor types and degrees of exposure.

Laws are now in force that set standards for protective clothing and regulate the record keeping of data about any possible exposure. Other areas that need close regulation include the use of respirator equipment when asbestos levels are above a specified level, appropriate labeling of materials that contain asbestos, and air and water safety. Employers must provide mandatory medical examinations at specified intervals for workers who are exposed to asbestos.

[references]

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4. King TE. Abestos-related pleuropulmonary disease. UpTodate. Last updated January 8, 2020.  Accessed 20200205.