Immune response due to silica exposure in Egyptian phosphate mines.

Silicosis is the most common occupational lung disease in Egypt where its prevalence rate ranges from 18.5 % to 45.8% among workers exposed to free crystalline silica dust. Despite its high prevalence, there is a lack of enforcement of exposure limits, availability and use of personal protective equipment, and occupational health education programs. These factors led the authors to study this unique working population; to the best of our knowledge, this is the first work that investigates the effect of exposure to crystalline silica on select immune response of exposed Egyptian phosphate miners. The main aims of this study were to investigate the effect of exposure to free crystalline silica on pulmonary function parameters and select immune response of exposed Egyptian phosphate miners. The study involved of three groups: 50 silica-exposed workers with radiological evidence of silicosis, 50 silica-exposed workers without evidence of silicosis, and 50 healthy unexposed subjects. There were significant differences between pulmonary function parameters in exposed groups with and without silicosis, and healthy unexposed control subjects (p<.001) and pulmonary function was significantly correlated with duration of silica exposure. Smoking had an additive effect on reduction of pulmonary function. Average values of C-reactive protein, rheumatoid factor, complement component C3, IgA, IgG, and IgM were significantly higher in the exposed group with silicosis than in the exposed group without silicosis and in healthy unexposed control subjects (p<.001).