FURTHER EVIDENCE OF HUMAN SILICA NEPHROTOXICITY IN OCCUPATIONALLY EXPOSED WORKERS

It has previously been shown that granite workers with heavy 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). The investigation was replic ated in another group of granite workers to further elucidate the expo sure effect relation. The urinary excretion of albumin, alpha-1-microg lobulin (AMG), beta-2-microglobulin (BMG), and beta-N-acetyl-glucosami nidase (NAG) was determined in two groups of granite workers with low and high exposure to silica. Low molecular weight proteinuria and enzy muria were significantly correlated with duration of exposure in the h igh but not the low exposure group.. These increases were most pronoun ced in those with 10 or more years of heavy exposure, and in those wit h radiological evidence of pulmonary fibrosis, particularly those with rounded small opacities denoting classical silicosis. These results p rovide further evidence that prolonged and heavy exposure to silica is associated with nephrotoxic effects in granite workers.