Subclinical nephrotoxicity associated with occupational silica exposure among male Kenyan industrial workers

Abstract

Objective: To determine early signs of renal injury due to occupational silica exposure. Design: Cross-sectional analytical research. Settings: Kenyatta National Hospital for the referent population and Clayworks ceramics, bricks and tiles factory for the assessment of occupational silica exposure. Subjects: Thirty three non-smoking silica-exposed male industrial workers and 38 non-smoking male referents participated in this study. Results: Silica-exposed males excreted significantly increased levels of U.TP, U.Malb, U.ALP, U.y-GT and U.LDH compared to referent males. Among the silica-exposed males, U.Si negatively correlated significantly with age, U.TP correlated significantly to each of U.ALP and U.LDH. However, no correlation was observed between work duration and U.Si. Conclusion: The present study shows that there is associated glomerular and proximal tubular damage among silica exposed workers which is not duration related and is seemingly subclinical and nonprogressive and urinary silica levels appears to be similar in all groups and are not affected by exposure and work duration: the reason for which is unclear.

Demonstration of Subclinical Early Nephrotoxicity Induced by Occupational Exposure to Silica among Workers in Pottery Industry

“…15 These findings were in line with those of other investigators who report that crystalline silica exposure results in an elevation of urinary proteins a r t i c l e among silica-exposed industrial workers. 2,3,16,17 The significant elevation of urinary ALP, g-GT, and LDH among silica-exposed group compared to their controls suggested renal tubular affection and agreed with the results of previous studies that report significantly increased biomarkers for renal proximal tubular dysfunction such as urinary retinol-binding protein (RBP) and urinary N-acetyl-β-D-glucosaminidase (NAG) among silica-exposed industrial workers. 2,18,19 More recent studies used the same urinary enzymes (ALP, g-GT, and LDH) to detect early signs of subclinical nephropathic tubular effect among silicaexposed workers 3 and among patients with diabetes.…”

“…Each urine sample was analyzed to assess glomerular integrity through measuring urinary levels of total protein (TP) using the semiautomated Technicon Bayer RA 1000 ® analyzer (Ireland Technicon Limited), and microalbumin (Malb) using Hemocue ® urine albumin system (Hemocue AB, Angelhom, Sweden); proximal and distal tubular structural integrity by determining urinary activities of g-GT and ALP, which are proximal tubule enzymes, and LDH located at distal tubular cells, 13 using automated Olympus AU640 ® analyser (Japan Mishima Olympus Optical Company Limited); and urinary silicon levels using the Buck Model 210 VGP Atomic Absorption Spectrophotometer ® (Bulk Scientific, Inc). 3 Urine level of KIM-1 was determined using a commercially available quantitative sandwich immunoassay technique (SunRed Biotechnology Company, Shanghai, China), as per manufacturers' instructions. Urinary KIM-1 level was normalized by dividing by urine creatinine.…”

“…Additionally, it was demonstrated that silica exposed workers can experience distinct renal histologic alterations in glomerular and proximal tubules. 2,3 Various urinary biomarkers have been proved to be useful to locate defects in specific parts of the nephron and can detect early renal changes resulted from exposure to nephrotoxins. These biomarkers include high molecular-weight protein, and albumin for evaluating glomerular integrity-low molecular weight protein for assessing tubular protein reabsorption.…”

“…Referring to several recent human studies, these urinary biomarkers have been used to detect early subclinical renal dysfunction. [3][4][5] Another novel urinary biomarker that has recently been shown to have more sensitivity and specificity in the detection of the initial preclinical renal tubular insult, is the urinary kidney injury molecule-1 (KIM-1). A meta-analysis including 11 studies (2979 patients) estimates the urinary KIM-1 specificity for the diagnosis of acute renal injury at 86% and sensitivity at 74%.…”

Study the Renal Affection Due to Silica Exposure Among Marble Cutting Workers

“…Sherson and Jorgensen(1989) studied morphologic changes in kidneys of patients after silica exposure under light and electron microscopy and found that tubular alterations were confined to proximal convoluted tubules. Other researchers also demonstrated an increased urinary excretion of albumin, transferrin, retinol-binding protein and N-acetyl-beta-D-glucosaminidase , α 1 microglobulin in the exposed group to silica (Mwangi et al, 2009). Ng and his colleagues (1993) reported that exposure to silica had glomerular and proximal tubular dysfunction evidenced by increased urinary excretions of albumin, alpha-1-microglobulin (AMG), and beta-N-acetyl-glucosaminidase (NAG).…”