Silicosis

What is silicosis?

Silicosis is an occupational lung disease that develops over time when dust that contains silica is inhaled into the lungs. Other examples of occupational lung disease include coalworker's pneumoconiosis and asbestosis.

Symptoms

Damage to the lung tissue means the lungs can't perform their function of supplying oxygen to the blood as well as they should. The symptoms resulting from this include:

• a cough, with or without sputum
• shortness of breath, particularly on exertion
• chest tightness

In the most common form of the disease, chronic silicosis, these symptoms develop over many years of exposure. The lung tissue becomes irreversibly damaged by fibrosis and is replaced with solid nodules of scar tissue.

In the rarer form, acute silicosis, the symptoms develop quickly after only a short period of exposure to high levels of silica dust. People with this acute form usually die within a year.

The damage suffered by the lungs leaves a person susceptible to lung infections, in particular TB. Smoking not only aggravates the symptoms of silicosis but also speeds up the progress of the disease. For this reason, it's essential that those diagnosed with silicosis are helped to stop smoking.

Causes and risk factors

Silica in crystalline form is toxic to the lining of the lungs. When the two come into contact, a strong inflammatory reaction occurs. Over time this inflammation causes the lung tissue to become irreversibly thickened and scarred - a condition known as fibrosis.

Common sources of crystalline silica dust include:

• Sandstone
• Granite
• Slate
• Coal
• Pure silica sand

People who work with these materials, as well as foundry workers, potters and sandblasters, are most at risk. Other forms of silica, such as glass, are less of a health risk as they aren't as toxic to the lungs.

Men tend to be affected more often than women, as they are more likely to have been exposed to silica.

Silicosis is most commonly diagnosed in people over 40, as it usually takes years of exposure before the gradually progressive lung damage becomes apparent.

There are now fewer than 100 new cases of silicosis diagnosed each year in the UK. This is mostly the result of better working practices, such as wet drilling, appropriate ventilation, dust-control facilities, showers and the use of face masks. Many foundries are also replacing silica sand with synthetic materials.

With these measures and an increased awareness of the risks of silica exposure, the number of cases should fall even further in the future.

When silicosis is suspected, a chest x-ray will look for any damaged areas of the lungs to confirm the diagnosis. Lung function tests are often performed to assess the amount of damage the lungs have suffered and to guide treatment.

Treatment and recovery

There's no cure for silicosis. It's essential, however, that the person affected removes any risk of further silica exposure and stops smoking. Prevention of any other lung disease which would further damage the remaining health lung tissue is important, so, immunisation against winter flu is recommended. People with silicosis should also be vaccinated against pneumococcal infection, a common cause of pneumonia.

Treatment to reduce inflammation and improve lung function may help and home oxygen therapy can be provided to help with breathing difficulties.