CHROMIUM-INDUCED EARLY CHANGES IN RENAL-FUNCTION AMONG FERROCHROMIUM-PRODUCING WORKERS

Urinary biochemical indicators of renal injury were examined in 84 mal e and 38 female ferrochromium-producing workers exposed to water-solub le chromium compounds [Cr(VI)]. The indicators examined included urina ry chromium (U-Cr), alkaline phosphatase (ALP), gamma-glutamyl transfe rase (gamma-GT), glutamic-oxalacetic and glutamic-pyruvic transaminase s (GOT and GPT), lactate dehydrogenase (LDH), N-acetyl-beta-D-glucosam inidase (NAG), total protein (TPr) and beta(2)-microglobulin (beta(2)- MG). The U-Cr levels in the exposed group were approximately 1.8 times that of the control group. Compared to controls, the activities of ga mma-GT, NAG, ALP, GOT and LDH in the urine of workers were significant ly increased whenever U-Cr concentration exceeded 45 mu g/g creatinine . The activities of gamma-GT, GOT and NAG were elevated in workers emp loyed for longer than ten years. However, no clear dose-response relat ionships nor time-effect relationships were found. The present results suggest that longterm exposure to water-soluble chromium [Cr(VI)] pro duces chronic renal injury. The site of the injury appears to mainly i nvolve the proximal tubule. U-Cr concentrations of >15 mu g/g creatini ne can be proposed as a threshold dosage for nephrotoxicity, and gamma -GT, NAG and ALP are early sensitive indicators of the most valuable f or evaluating the renal injury.