Sex differences in the relationship between blood mercury concentration and metabolic syndrome risk

Background: Mercury exposure enhances free radical production and reduces activity of anti-oxidant enzymes, resulting in detrimental health effects. Some researchers have reported an association between blood mercury and increased risk of metabolic syndrome (MetS); however, sex differences in the relationship were not fully considered. Aim: To examine the sex differences in the relationship between blood mercury concentration and the increased risk of MetS in Korean men and women. Materials and methods: A nationwide cross-sectional study was conducted to examine the relationship between blood mercury concentration and MetS in 2,976 men and 3,074 women over 19 years of age (aged 19-87 years), using data from the 2010-2012 Korean National Health and Nutrition Examination Survey (KNHANES-V). Multiple logistic regression analysis was used to assess the relationship between blood mercury concentration and the prevalence risk of MetS after adjusting for confounding variables. Results: Compared to the lowest quartile of blood mercury concentration, the OR (95% CI) for MetS of the highest quartile in men was 1.62 (1.15-2.28) after adjusting for age, smoking status, alcohol consumption, regular exercise, and BMI. Similarly, in multiple logistic regression analysis using log2-transformed blood mercury as a continuous variable, the OR (95% CI) for having MetS with doubling of blood mercury was 1.20 (1.05-1.36) after adjusting for the same co-variables. However, the relationship was not observed in women after adjusting for the same co-variables. Conclusions: Blood mercury concentration was independently associated with an increased risk of MetS in men.