Renal tubular function of cadmium exposed workers

The kidney is considered the critical organ following long term occupational or environmental exposure to cadmium. Tubular dysfunction in the form of low molecular weight proteinuria is the earliest manifestation of cadmium nephrotoxicity. The current acceptable critical concentration of cadmium in the urine is 10 ug Cd/g creatinine. The aim of this paper is to identify the presence of tubular dysfunction among workers with less than 10 ug Cd/g creatinine. The exposed group of 92 workers were from a nickel-cadmium battery factory. The control group of 122 workers were factory and sedentary office workers with no known history of exposure to nephrotoxic agents. The urinary excretion of N-acetyl-D-glucosaminidase (NAG), beta-2-microglobulin (beta 2m) and alpha-1-microglobulins (alpha 1m) were measured from morning spot urine samples. The age, sex and race adjusted NAG and alpha 1m showed increasing trend with rising urinary cadmium levels. Levels were significantly raised when the urinary cadmium was above 5 ug Cd/g creatinine. A similar trend was seen with increasing length of exposure. Renal tubular dysfunction is present among cadmium exposed workers with levels below the current critical concentration.