EFFECTS OF ELEMENTAL MERCURY EXPOSURE AT A THERMOMETER PLANT

This study compares 84 mercury-exposed workers at a thermometer manufacturing facility with 79 unexposed workers for evidence of chronic mercury toxicity. Personal breathing-zone air concentrations of mercury ranged from 25.6 to 270.6-mu-g/m3 for thermometer workers. Urinary mercury levels in the study population ranged from 1.3 to 344.5-mu-g/g creatinine, with eight (10%) participants exceeding 150-mu-g/g creatinine and three workers exceeding 300-mu-g/g creatinine, which indicates increased absorption of mercury among the thermometer workers. All urine mercury levels in the comparison group were compatible with normal background levels in unexposed adults (< 10-mu-g/g creatinine). Thermometer plant workers reported more symptoms than did controls; in general, these differences were not statistically significant and could not be specifically associated with mercury exposure. Static tremor, abnormal Romberg test, dysdiadochokinesia, and difficulty with heel-to-toe gait were more prevalent among thermometer workers than control workers, which could not be associated with recent mercury exposure; there was some suggestion of an association with chronic exposure. There were no intergroup differences for the standard clinical tests of renal function except for a significantly higher mean specific gravity among the thermometer workers. A positive correlation was found, however, between urinary N-acetyl-b-D-glucosaminidase (NAG) and urinary mercury. There was no consistent evidence for intergroup differences in proximal renal tubule function, as measured by urinary beta-2-microglobulin (B2M) or retinol binding protein (RBP).