An underestimated extra-pulmonary effect of silica dust exposure: Renal affection

Occupational exposure to silica dust is a common health hazard in developing countries leading mainly to silicosis. About 40,000 workers are estimated to be exposed to silica in Egypt. Microalbumenuria is considered to be an early marker of nephropathy. The objective of the present work was to identify the possibility of renal affection among workers exposed to silica with and without silicosis. A cross-sectional study included randomly selected 3 groups; (exposed silicotic group, exposed non-silicotic and non-exposed group) each of 27 matched male workers and free from chronic diseases that may induce nephropathy; from a factory for refractories in Alexandria. According to a parallel environmental survey, exposure levels to respirable free silica in the milling, mixing and production departments of the plant were identified.    All participants were subjected to a predesigned questionnaire, clinical examination, anthropometric measurements, a standard chest radiological examination and measurement of urinary albumen creatinine (UAC) ratio.

Preliminary results showed that 52% of the exposed workers with silicosis, 40.7% of exposed workers with no silicosis, and 7.4% of non-exposed workers had microalbuminurea with no statistically significant difference between the silicotic and the non-silicotic workers. Multiple regression analysis revealed that the most important predictors of urinary albumen level were age, duration of exposure and level of exposure to silica. The pneumoconiotic score was not significantly related to UAC ratio. In conclusion, screening for UAC ratio is suggested to be included in periodic medical examination of silica exposed workers. New industrial policies should emphasize effective exposure control stratigies.