This disease is becoming rare as the standards of industrial hygiene improve. It is caused by the inhalation of fine free crystalline silicone dioxide dust or quartz particles.
Occupation associated with silicosis
- Mining-coal, tin, gold, other minerals
- Quarrying
- Dressing of sandstones and granite
- The pottery and ceramics industry
- Manufacture of silica blocks and abrasive soaps
- Iron and steel industries
- Sand-blasting
- Metal grinding
- Boiler scaling
Silica is a most fibrogenic dust and causes the development of hard nodules which coalesce as the disease progresses. Tuberculosis may modify the silicotic process with ensuing caseation and calcification. The radiological features are similar to those seen in coal workers pneumoconiosis though the changes tend to be more marked in the upper zones. The hilar shadows may be enlarged and 'egg-shell' calcification in the hilar lymph nodes is a distinctive feature but does not occur in all patients. The disease progresses even when exposure to dust ceases. The patient should, therefore, be removed from offending environment as soon as possible.
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