RENAL AFFECTION AND SOME OXIDATIVE STRESS BIOMARKERS AMONG WORKERS EXPOSED TO SILICA DUST

Abstract

Occupational exposure to silica dust especially its crystalline form is primarily related to silicosis. Other possible silica related diseases such as renal disorders are still underestimated. The objective of the present work was to study the posibility of renal affection; as well as, alterations of some oxidative stress and autoimmune biomarkersamong workers exposed to silica dust with and without silicosis. Methods: A crosssectional study was conducted in one of the factories for refractories in Alexandria,Egypt. The sample was divided into 3 groups; exposed silicotic, exposed non-silicotic and non-exposed group. Each group consisted of 27 workers. According to a parallel environmental survey, exposure levels to respirable free silica in the three departments of the plant namely; milling, mixing and production were identified. All participants were subjected to a predesigned questionnaire, clinical examination, anthropometricmeasurements, a standard chest radiological examination and laboratory investigations namely urinary albumin, antioxidants activity (SOD) and glutathione S-transferase and serum anti-neutrophil cytoplasmic antibodies (ANCA).Results: The study shows that about 52% of the exposed workers with silicosis, 40.7% of exposed workers with no silicosis, and 7.4% of non-exposed workers had microalbuminurea. There was no statistically significant difference in urinary albumin levels between exposed silicotic and exposed non-silicotic workers. There was a statistically significant difference between the 3 groups regarding their antioxidants levels. Qualitative ANCA testing results were negative for all workers. Multiple regression analysis showed that the most important predictors of urinary albumin level were age, duration of exposure, level of exposure to silica, SOD and Glutathione S-transferase (Adjusted R² = 0.387); the most important predictors of SOD level were duration of exposure and level of exposure to silica (Adjusted R² = 0.692); and that the most important predictors of Glutathione S-transferase level were duration of exposure, level of exposure to silica and pneumoconiotic score (Adjusted R² = 0.657).Conclusion, long-term exposure to silica dust may induce oxidative stress which plays a possible role in the renal affection among exposed workers with or without silicosis.