Neuropsychological effects of long-term occupational exposure to mercury among chloralkali workers

BACKGROUND: Mercury is one of the most well-known toxic metals for humans. Chloralkali workers are exposed to mercury vapours extensively, which may be associated with neurotoxicity. OBJECTIVE: The aim of this study was to determine the associations between mercury concentration in blood and air samples, and mercury's neuropsychological effects among chloralkali workers. METHODS: This study was conducted on 50 chloralkali workers as the exposed group and 50 non-industrial office workers as the unexposed group. All subjects were assessed using the Hamilton Depression Rating Scale, Piper Chronic Fatigue Scale and Essential Tremor Rating Scale. Mercury concentration was measured in blood and air samples using cold vapour atomic absorption spectrometry. RESULTS: There was significantly more severe fatigue, depression and tremor in the exposed group compared with the unexposed group. The mean concentration of blood mercury in the exposed group was 22.59 +/- 12.5 mu gL(-1) which was significantly higher than the unexposed group (1.28 +/- 1.05 mu g L-1). Based on multiple linear regression, shift work, smoking, fatigue, depression and tremor were predictor variables for blood mercury concentration. CONCLUSIONS: This study indicated that this sample of chloralkali workers suffered from neuropsychological problems such as fatigue, depression and tremor, which is probably related to mercury exposure.