Silica Exposure, Dust Inhalation – Signs, Symptoms of Silicosis

Silicosis is one of the most widely seen occupational diseases. It arises from inhalation of silica particles with subsequent chronic lung disease that develops over years and decades. Most patients are asymptomatic for decades and present with the first symptoms after 10 to 20 years. This is the classic chronic form of silicosis. Accelerated silicosis is where the symptoms are seen much earlier, typically within 5 to 10 years after exposure. In acute silicosis, patients present with symptoms within weeks or months.

Silicosis is a type of pneumoconiosis – lung diseases that are caused by inhalation of mineral dusts. The other common diseases in this category includes asbestosis (asbestos fibers) and coal worker’s pneumoconiosis (coal particles). The symptoms of silicosis are non-specific and may be seen with many other respiratory conditions. Intensity of silicosis symptoms depends on the duration and quantity of silica dust inhalation.

  • Shorter duration of exposure and inhalation of minimal amounts of silica (simple silicosis) :
    • Development of tiny nodules does not compromise lung function.
    • Patients may therefore remain asymptomatic for much longer periods of time.
    • Silicosis may only be diagnosed during screening for other respiratory conditions.
  • Longer duration of exposure to silica and inhalation of larger amounts of silica (complicated silicosis) :
    • Larger nodules of fibrous scarring evident on chest x-ray/CT.
    • Nodules eventually coalesce to form extensive scarring throughout the affected areas of the lung -gas exchange and lung elasticity is compromised.
    • There is an increased chance of tuberculosis (TB), COPD and lung cancer which may contribute to the clinical presentation.

Signs and Symptoms of Silicosis

The signs and symptoms of silicosis is similar to the other common types of pneumoconiosis – asbestosis and coal worker’s pneumoconiosis. Difficulty breathing, coughing and susceptibility to repeated respiratory infections are common features. Cyanosis and clubbing may be seen in advanced cases. Abnormal pulmonary function tests revealing diminished lung volume and poor gas perfusion is common. Pulmonary hypertension and right sided heart failure will contribute to other signs like peripheral edema (swelling of the legs).

Silicosis Difficulty Breathing

Difficulty breathing (dyspnea) is among the first symptoms to become apparent. It is usually only evident upon exertion (exertional dyspnea) and gradually progresses to the point where it persists even at rest. Abnormal breathing sounds like crackles and wheezing may be seen with time. In smokers, emphysema and chronic bronchitis should first be excluded as possible causes of dyspnea.

Silicosis Cough

Coughing associated with silicosis is largely a productive cough. It is exacerbated with superimposed infections and  has to be differentiated from chronic bronchitis, especially in smokers. Hemoptysis (coughing up blood) may be more prominent in patients with tuberculosis (silicotuberculosis).

Acute Silicosis

The clinical presentation between chronic, accelerated and acute silicosis is largely the same. However in acute silicosis, the symptoms tend to develop and progress much sooner. Pleuritic pain, weight loss and malaise are prominent with acute silicosis and culminates with respiratory failure within 18 to 24 months.

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