Silicosis

Silicosis is a scarring disease of the lungs caused by inhaling fine particles of crystalline silica dust.  Silica dust particles can trigger an inflammatory reaction that leads to the formation of lung nodules and scars. These changes can lead to loss of lung function. The disease typically takes 5–20 years to appear after first exposure. Dry cough and shortness of breath are early symptoms of the disease. Silicosis can worsen over time, especially with continued dust exposure. Lung function often declines as the chest x-ray worsens, and lung scarring may lead to decreased oxygen levels and substantial disability. There is no cure for silicosis, so prevention is essential. 

Who gets silicosis?

People who work in the following industries may have exposure to silica dust:

• Artificial/engineered or natural stone fabrication   
• Mining (coal, metal/nonmetal, stone, sand, gravel, and other commodities)
• Concrete mixing and cutting           
• Brick and stone cutting
• Sandblasting  
• Foundry work
• Construction  
• Fracking (natural gas extraction)
• Pottery making

What other diseases are associated with exposure to respirable silica dust?

• Chronic Obstructive Pulmonary Disease (COPD)
• Emphysema
• Tuberculosis (TB) and other lung infections
• Lung cancer
• Kidney disease
• Autoimmune diseases such as rheumatoid arthritis or scleroderma

Silicosis is an ancient disease? Why is this important now?

Exposure to silica dust has been known to cause silicosis for centuries, yet many cases continue to occur in the United States and worldwide. More than 2 million people in the U.S. are exposed to silica dust at work. The latest (2017) Occupational Safety and Health Administration (OSHA) Silica Standard has specific requirements for screening workers based on exposure levels to silica dust.

There are several ways to control exposure to silica and keep dust levels low so people are not at risk. Ventilation systems and other engineering controls can be used to minimize dust exposure. Wet methods attached to equipment for grinding, cutting, sawing, and polishing can help keep dust levels low. Good cleaning practices like avoiding dry sweeping of dust containing silica and use of approved respirators are other possible strategies for minimizing exposure. 

There is no cure for silicosis, but it is preventable. If workers are diagnosed with silicosis, they should be removed from exposure to minimize the risk for progression of lung disease and other disease complications of silica exposure.

What resources are available for silicosis patients?

If you have questions about silicosis, you can call the toll free number for the National Jewish Health Program on Silicosis and Its Prevention at 877.255.5864 (option 2).

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Silicosis: Causes

Silicosis is caused by breathing in high concentrations of silica dust, usually over several years. Shorter periods of more intense exposure may also cause silicosis.

When silica dust enters the lungs, it causes the formation of scar tissue, which makes it difficult for the lungs to absorb oxygen. The silica dust may also cause enlargement and calcification of chest lymph nodes. Silicosis may develop and progress while a worker remains exposed or after exposure to crystalline silica has ended.

Crystalline silica comes in several mineral forms — quartz, tridymite and cristobalite. Natural stone sources of crystalline silica include sandstone, granite, and marble. Engineered (artificial) stone typically contains high concentrations of crystalline silica mixed with resins and metal pigments. Some examples of industries where workers may be exposed to silica dust include:

• Engineered or natural stone fabrication   
• Mining (coal, metal/nonmetal, stone, sand, gravel, and other commodities)
• Concrete mixing and cutting           
• Brick and stone cutting
• Sandblasting  
• Foundry work
• Construction  
• Fracking (natural gas extraction)
• Pottery making

Silicosis: Diagnosis

If you work in an industry where you have been exposed to silica dust, it’s important to get regular checkups. Silicosis is diagnosed when clinicians take an occupational history and perform additional testing. 

The disease may not show up for 5-20 years after exposure, so it is important to consider all jobs throughout your career. If your work history indicates that there may have been exposure to respirable crystalline silica, your medical provider may order the following tests to find out if there is a possible diagnosis of silicosis:

• Imaging studies such as a chest x-ray or a more detailed study of the lungs with a chest computed tomography (CT) scan are used to visualize the lung tissue and lymph nodes. Physicians trained as B-readers (physicians with special expertise in reviewing X-rays for dust related illnesses) may interpret the chest x-ray to determine whether a dust induced lung disease is present.
• Lung function testing (also called pulmonary function testing [PFT]) may be performed to determine how much air your lungs can hold, how quickly you can expel air from your lungs, and how well your lungs can absorb oxygen.
• An arterial blood gas (ABG) at rest and with exertion may be performed to measure oxygen and carbon dioxide levels in the blood and to determine if supplemental oxygen is needed.
• Laboratory testing for tuberculosis (TB), autoimmune disease, kidney disease, and other studies may be needed, as these diseases are often associated with silicosis.
• On rare occasions, a lung biopsy may be needed to verify the diagnosis of silicosis. A bronchoscopy, in which a long, thin tube with a tiny camera is inserted into your lungs, may be used to check for lung tissue damage and/or infection.  Occasionally, a surgical lung biopsy may be needed for diagnosis.

Silicosis: Symptoms

Silicosis is a progressive disease, meaning that it often gets worse over time as lung scarring occurs. It may start out as an abnormal x-ray. 

Early silicosis, usually detectable on chest imaging, may cause no symptoms or loss of lung function. More severe forms of silica-related lung disease usually lead to loss of lung function and respiratory symptoms of shortness of breath and cough.

Symptoms of silicosis may appear within a few months to many years after exposure.  Some of the symptoms of silicosis include:

• Chronic, nagging cough
• Shortness of breath with exercise
• Weakness and fatigue
• Fever
• Weight loss
• Night sweats

These symptoms can worsen over time as the disease progresses. Some people may eventually have difficulty doing simple activities of daily living. That’s why it’s important to seek treatment for silicosis early, before symptoms become severe.

Because silicosis affects the immune system, exposure to silica increases the risk of lung infections, such as tuberculosis. Exposure to silica also increases the risk of developing lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease, so you should also watch for the symptoms of these illnesses.

Autoimmune complications also are possible with silicosis, such as connective tissue diseases like rheumatoid arthritis, scleroderma, and systemic lupus erythematosus (SLE, also known as lupus).

Silicosis: Treatment

There is no cure for silicosis and no medications that can reverse the lung damage that has already been done. This means that reducing and controlling exposure to silica dust is the only effective defense against silica-related lung disease.

If you have been exposed to silica dust in your job, it’s important to be checked regularly by a medical provider. The earlier a diagnosis of silicosis can be made, the more helpful it can be to avoid worsening silicosis and its complication. Treatment will be specific to your symptoms, so it will vary for each individual. Silicosis treatment is supportive and includes:

• Inhalers, if lung function testing indicates that such treatment would be helpful
• Timely treatment of respiratory infections. Silicosis makes you more susceptible to infections, so it’s important that you watch for them and see your doctor right away if one develops.
• Surveillance for mycobacterial lung infections, autoimmune diseases, lung cancer, and kidney disease.
• Immunizations for influenza, pneumococcal pneumonia and other recommended vaccinations. It’s important to get your flu vaccination every year.
• Supplemental oxygen at rest and/or with exertion if needed.
• Smoking cessation. If you are a smoker, one of the most important things you can do to reduce respiratory symptoms and worsening disease is to quit smoking. Smoking damages your lungs and aggravates the effects of silicosis.
• A program of regular exercise to maintain overall health, weight control, and respiratory muscle strength
• Pulmonary rehabilitation
• Lung transplant may be considered in some cases.