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.