Effects of exposure to elemental mercury on the nervous system and the kidneys of workers producing natural gas.

Early signs of alterations in renal and neurological functions were studied in three groups of workers who were exposed to different levels of mercury that were below the current biological exposure index of 35 microg/g creatinine. There were no differences among the three study groups with respect to either motor nerve conduction velocity or tremor frequency spectra of physiological tremors. Also, no significant correlations were found between the results of the neurological tests and any of the present or historical biological monitoring data. In contrast, N-acetyl-beta-D-glucosaminidase was increased significantly in the group with the higher exposure, compared with either the lower-exposure or control groups. N-acetyl-beta-D-glucosaminidase was correlated strongly with mercury concentration in urine and was correlated weakly with historical biological monitoring data; however, there was no correlation with duration of exposure. These results suggest that after exposure to mercury at levels below the biological exposure index, a transient increase in N-acetyl-beta-D-glucosaminidase can be observed, but is not an early indicator of developing renal dysfunction.