What is silicosis?
Silicosis is a lung disease that arises with inhaling silica particles. It is a slowly progressing disease that takes years or even decades before symptoms may become apparent. Recently, the condition has come to the forefront in the South African media due to pending litigation by mineworkers. Globally, silicosis is one of the most common occupational lung diseases.
Patients with silicosis usually do not know that they have the disease. Eventually there may be symptoms like shortness of breath, coughing and chest pain with tiredness and weight loss over time. The symptoms are commonly mistaken for TB (tuberculosis) but silicosis is not a lung infection like TB. However, patients with silicosis are at a higher risk of developing TB.
Types of Silicosis
There are three types of silicosis depending on the quantity and duration of exposure to silica particles.
- Acute silicosis occurs with exposure to very large amount of silica even over a short period of time. The first symptoms become evident within weeks or months after exposure.
- Accelerated silicosis occurs when a person is exposed to a fairly large amount of silica over a short period of time like 5 to 15 years. Symptoms become evident after years or decades.
- Chronic silicosis is the more common form of the lung disease that is seen globally. It arises with long term exposure to even small amounts of silica. Usually a person is exposed to silica for 20 years or more.
Silicosis is only one type of occupation lung disease. It is known as a pneumoconiosis, a type of lung disease caused by certain types of dust particles, for example asbestosis caused by asbestos and coal worker’s pneumoconiosis caused by inhaling coal dust. The symptoms of most types of pneumoconiosis are largely the same, as is the case with chronic lung infections. Therefore the symptoms of silicosis when it becomes apparent are often misdiagnosed at the outset.
The two main symptoms seen in silicosis is difficulty breathing and a persistent cough. In acute silicosis, the person may experience respiratory distress as the blood oxygen levels drop to a very low level. Weight loss is a common long term symptom. The patient typically feels very tired and there is a general sense of being unwell (malaise). Silicosis patients are at a higher risk of developing TB and when both lung diseases occur simultaneously, it is referred to as silicotuberculosis. Coughing up blood is commonly seen in these patients.
Other symptoms like fever, night sweats and chest pain are more likely due to lung infections that frequently arises in silicosis. As the condition advances, the person may become pale in colour with tinges of blue seen on the skin (cyanosis). This is a sign of inadequate gas perfusion of the blood. Changes in the fingers known as clubbing arise as a late symptom in chronic silicosis. Eventually there may be pulmonary hypertension and signs of right side heart failure.
Causes of Silicosis
Silicosis is a lung disease that arises with inhalation of silica particles. The form and progression of the disease depends on the quantity and duration of exposure to silica particles. Silica is present throughout the globe and exposure is primarily through work with sand and rock. Quarry workers, miners, rock drillers, mine ore workers and construction workers digging tunnels are all at high risk of silicosis. It may also be seen among workers in the glass and stone industry as well as with sandblasting.
When silica dust is inhaled, it can travel through the airways to lodge in the lung. Here immune cells try to consume the particles and in the process release chemicals that cause lung inflammation. Silica cannot be adequately disposed of and remains in the lungs for months, years or even decades. Exposure to silica also causes the build up of free radicals in healthy lung tissue further damaging it.
Prolonged inflammation eventually leads to the formation of scar tissue. This scar tissue develops extensively in the lung thereby compromising the function of the otherwise thin and flexible lung tissue. It hampers the exchange of gas between the air and bloodstream across the normally thin lung tissue. Gradually the disease progresses until lung function is severely compromised.
Diagnostic Tests for Silicosis
The main factor is diagnosing silicosis lung disease is a history of the patient being exposed to silica particles. Diagnostic tests that would also be conducted by a medical professional includes :
- Chest x-ray and CT scan
- Pulmonary function tests
- Tuberculosis tests
- Blood tests for connective tissue disorders
There is no specific treatment or cure for silicosis. It is a chronic progressive lung disease meaning that the lung damage is irreversible and gradually gets worse over time. The first step is to ensure that patients with silicosis are no longer exposed to large amounts of silica. Secondly, supportive measures are instituted to minimise the severity of symptoms and help the patient cope with daily life. This may involve the use of :
- Cough medicines
Patients may also need antibiotics as they very often develop lung infections. In very severe cases of silicosis, a lung transplant may be necessary.