Positive Health Online

Abstract

KOBAL and colleagues, Idrija Mercury Mine, Idrija, Slovenia, have studied the impact of long-term exposure to mercury on antioxidative capacity and lipid peroxidation in mercury miners.

Background

Limited information is available on the effects of chronic mercury exposure on the risk of cardiovascular disease. It is known that mercury can promote lipid peroxidation. The aim of the study was to test the hypothesis that long-term past occupational exposure to elemental mercury can modify antioxidative capacity and promote lipid peroxidation in miners.

Methodology

54 mercury miners and 58 workers as the control group were evaluated for their previous exposure to mercury and the main behavioural and biological risk factors for cardiovascular disease. The following parameters were determined: 1) Mercury and Selenium levels in blood and urine; 2) antioxidative enzymes, superoxide dismutase, catalase, and glutathione peroxidase activity in erythrocytes as indirect indices of free radical activity; 3) melatonin in blood and urine; and 4) lipid hydroperoxides and malondialdehyde as lipid peroxidation products.

Results

The miners were intermittently exposed to mercury for periods of 7 to 31 years The cumulative mercury peak level varied from 794-11,365 micrograms/L. The current blood and urine mercury concentrations were practically on the same level in miners and controls. Miners showed some neurotoxic and nephrotoxic sequelae of micromercurialism. No significant differences in behavioural and biological risk factors for cardiovascular disease were found between miners and controls. A weak correlation (p < 0.01) between systolic blood pressure and average past exposure level was found. The mean blood selenium levels in miners was significantly lower (p < 0.05) than in the controls, while the mean urine selenium tended to be higher (p < 0.05) in miners. Among antioxidant enzyme activities, only catalase in erythrocytes was significantly higher (p < 0.01) in miners than in the controls. The mean concentration of melatonin in miners was significantly higher (p < 0.01) than in the controls. Among the observed lipid peroxidation products, the mean concentration of malonedialdehyde was statistically higher (p < 0.01) in miners than in the controls. In the group of miners with high mercury accumulation and the presence of some nonspecific symptoms and signs of micromercurialism, the results of our study support the assumption that long-term occupational exposure to mercury enhances the formation of free radicals even several years after termination of occupational exposure.

Conclusion

Long-term occupational exposure to mercury could be one of the risk factors for increased lipid peroxidation and increased mortality due to ischaemic heart disease found among the mercury miners of the Idrija Mine.

References

Kobal AB, Horvat M, Prezelj M, Briski AS, Krsnik M, Dizdarevic T, Mazej D, Falnoga I, Stibilj V, Arneric N, Kobal D, Osredkar J. The impact of long-term past exposure to elemental mercury on antioxidative capacity and lipid peroxidation in mercury miners. Journal of Trace Elements in Medicine & Biology 17 (4): 261-274, 2004.