Health Risks of Silica Exposure and Medical Monitoring

Breathing in dust from crystalline silica-containing materials can lead to lung disease. Silica dust particles become trapped in lung tissue causing inflammation and scarring. The particles also reduce the lungs’ ability to take in oxygen. This condition is called silicosis. Silicosis results in permanent lung damage and is a progressive, debilitating, and sometimes fatal disease.

Chronic silicosis typically occurs after 10 or more years of exposure to respirable crystalline silica. However, the disease can occur much more quickly after heavy exposures. Silicosis can develop or progress even after workplace exposures have stopped.

Symptoms of silicosis may include:

• Cough
• Fatigue
• Shortness of breath
• Chest pain

There is no known cure for silicosis and some patients may require a lung transplant.

Workers exposed to silica and those who have silicosis are also at increased risk of tuberculosis (TB), a contagious and potentially life-threatening infection.

Exposure to respirable crystalline silica puts workers at risk for developing other serious diseases including:

• Lung Cancer
• Chronic Obstructive Pulmonary Disease (COPD)
• Kidney Disease
• Autoimmune Disease

Medical Monitoring

Medical monitoring or surveillance of workers can help identify health effects related to respirable crystalline silica exposure. An important concern is the risk of developing silicosis, a progressive and irreversible lung disease. Silica exposure can also impair lung function by causing COPD. Routine screening and surveillance for other diseases caused by silica is not required in the U.S.

As lung tissue turns into scar tissue with silicosis, reduced lung function occurs and gets progressively worse, even after dust exposure has ended.

For a clinician to make a diagnosis of silicosis, a worker needs to have a history of exposure to respirable crystalline silica and radiographic or histopathologic findings compatible with the disease. It is also important to exclude other possible causes of lung disease. Findings of silicosis can be seen with chest x-rays, but computerized tomography (CT scans) have greater sensitivity.

The time from initial exposure to when symptoms first appear (the latency period) with silicosis depends on duration and intensity of exposure. Higher exposures tend to result in shorter latency periods and faster disease development. The table below describes different types of silicosis.

The type with the quickest onset is acute silicosis. This can occur after only a few weeks or months exposure to very high levels of respirable crystalline silica. In acute silicosis, affected parts of the lung fill with fluid, typically causing severe illness or death.

Accelerated silicosis occurs after high levels of exposure and typically presents after 5 to 10 years. Chronic silicosis is the most common type. It occurs after 10 or more years of exposure to lower levels of silica. Both types of silicosis have the same radiographic appearance and are set apart based on their different latency periods.

Periodic medical monitoring helps to detect silicosis at early stages so workers can avoid further exposure and potentially limit progression of disease. Healthcare providers who suspect a patient’s health problems are caused by working with respirable crystalline silica should report the case to their local or state health department.