Effect of occupational mercury exposure on plasma lysosomal hydrolases

The activities of three plasma lysosomal hydrolases, beta-galactosidase, beta-glucuronidase and beta-N-acetylglucosaminidase, were studied in 20 workers exposed to metallic mercury vapor in a chlorine alkali plant and in 10 nonexposed referents. The urinary excretion and blood levels of mercury were determined on the day of study, and the history of mercury exposure was reviewed from the records of mercury concentrations in urine and blood over periods of up to 133 months. The average levels of beta-N-acetylglucosaminidase and beta-glucuronidase were higher in the plasma of exposed workers, but the difference was not significant. No significant positive correlation was seen between lyosomal enzyme activities and cumulative long-term exposure to mercury. It is concluded that measurement of plasma lysosomal hydrolase-activities is not of great value in the biological monitoring of workers exposed to low concentrations of metallic mercury vapor. In line with published data, the concentration of mercury showed a clear-cut diurnal variation in nonexposed persons, persons currently exposed and persons with a history of past exposure. The excretion rate of mercury remained constant throughout the day.