ABSTRACT
Chronic silicosis (nodular pulmonary fibrosis) has been recognized since ancient times as an occupational disease which afflicts people chronically exposed to dusts containing crystalline silica. Acute silicosis (alveolar proteinosis) usually occurs in occupations where silica is fractured or ground into fine powders by mechanical processes (drilling, sandblasting, etc.). In contrast to chronic silicosis, acute silicosis becomes clinically apparent within a few years of exposure and is a serious, often fatal disease, resulting from acute injury to alveolar lining cells. Bronchogenic carcinoma is a lung cancer which can occur in experimental animals exposed to silica dusts and is suspected to occur preferentially with patients with silicosis (IARC, 1997). It also is associated with smoking, which may act synergistically with silica or which may confound epidemiological evidence. Silica-related autoimmune diseases are typically systemic sclerosis, rheumatoid arthritis, lupus, and chronic renal disease.
