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[Early changes in renal injury parameters and their influencing factors in workers exposed to mercury].

OBJECTIVE
To investigate atmospheric mercury concentration in the workplace and urinary mercury concentration in workers exposed to mercury in a thermometer factory, and to determine the levels and influencing factors of urinary Β₂-microglobulin (Β₂-MG) and retinol-binding protein (RBP) in these workers.


METHODS
An occupational health survey of the workplace was completed according to relevant national occupational health standards. Questionnaire survey and occupational health examination were conducted in 178 workers exposed to mercury in the factory. Statistical analysis was accomplished using SPSS 19.0.


RESULTS
In the workplace, atmospheric mercury concentration was out of limits at seven of eight detection points expressed by short-term exposure limit; it was out of limits at all the eight detection points shown by time-weighted average. Statistically significant difference in atmospheric mercury concentration was found among different detection points (F = 138.714, P < 0.001). The geometric mean of urinary mercury concentration measured in 154 workers was 171.607 µg/g. There were 127 workers with urinary mercury concentration exceeding the standard (82.5% over-standard rate). Significant difference in urinary mercury concentration was shown in the workers among different positions (χ² = 44.531, P < 0.01). Urinary mercury concentration was positively correlated with atmospheric mercury concentration (r = 0.624, P < 0.01). The mean urinary Β₂-MG level measured in 148 workers was 0.142 mg/L, and seven workers had urinary Β₂-MG levels greater than 0.3 mg/L (4.7% abnormal rate). The mean urinary RBP level measured in 153 workers was 0.485 mg/L, and 19 workers had urinary RBP levels greater than 0.7 mg/L (12.4% abnormal rate). Ordinal logistic regression showed that age >34 years (OR = 4.88, 95%CI: 2.24∼10.62) and length of service >15 years (OR = 2.50, 95%CI: 1.06-5.92) were risk factors for increased urinary Β₂-MG level. Age >45 years (OR = 7.52, 95%CI: 2.50∼22.65) was a risk factor for increased urinary RBP level.


CONCLUSION
In the thermometer factory under study, atmospheric and urinary mercury concentrations both seriously exceeded the standards, which were harmful to the health of workers. High atmospheric mercury concentration, old age, and long length of service were risk factors for increased urinary Β₂-MG and RBP levels in workers exposed to mercury.