Background: Silica (SiO2), an abundant mineral found in sand, rock, and soil is an increasingly identified environmental nephrotoxin with fairly unique renal and systemic manifestations. Aim: To identify the relation between silica exposure among marble workers and renal diseases in order to early predict renal affection. Materials &Methods: This study was conducted in marble blasting area in El Maadi, in Cairo. The studied group included 25 workers in the marble blasting area. They were adult men aged between 18-42 years (26.5±7.8), working on the basis of 10 hours/day with one
day off per week. A referent group of 40 males matched for age ( that ranged from 21-41 yrs., 26.2±6.38), sex, socio-economic status, smoking habits selected from relatives of the Kasr Al Aini hospital patients, were also enrolled in our study. Each individual was subjected to detailed occupational and medical history taking and estimation of (A)
Environmental air measure of SiO2 : Using X-Ray Fluorescence Analysis at National Research Center , which demonstrates that silica in air is about 10 times exceeding the Egyptian standard for dust fall (B) Some biological analysis included renal urinary biomarkers . High-molecular-weight protein albumin (U.Malb), the low-molecular
-weight protein α1-microglobulin (α 1 - M), urea and creatinine, urinary creatinine and the lysosomal enzyme N-acetyl-β-D-glucosaminidase (NAG). Results: Our results showed a statistically significant difference between the exposed and the control groups as regards different renal biomarkers as urinary albumin, serum creatinine, urinary creatinine, blood urea, NAG and α 1 microglobulin in urine. We illustrated a statistically significant positive correlation coefficient between duration of exposure  to silica among the exposed group and urinary albumin, serum creatinine, N-acetylbeta-
D-glucosaminidase and α 1 microglobulin. We found also a statistically negative correlation coefficient between duration of exposure to silica among the exposed group and the urinary creatinine. We demonstrated a statistically positive significant correlation coefficient between the age of the workers and different investigations that indicates renal affection and we found also a statistically negative correlation coefficient between the level of serum creatinine and urinary creatinine. Conclusion: Our study demonstrated that occupational exposure to silica lead to subclinical signs
of nephrotoxicity. Periodic tests as NAG and α 1 microglobulin in urine should be done to detect early renal affection. We should also insist that workers exposed to silica dust must wear protective equipment, and encourage engineering control to reduce the level of silica in air.