The association between blood levels mercury and risk for obesity in a general adult population : results from the Korean national health and nutrition examination survey

Abstract

Objective: The rising prevalence of overweight and obesity has been recognized as a serious, worldwide public health concern in the 21st century. Many studies have reported about risk for gain weight according to countless causes of obesity. The primary objective of this study was to estimate association between blood mercury levels and obesity in Korean adults.

Methods: We analyzed cross-sectional data from 9,923 participants (4,619 men and 5,304 women) who completed the Korean National Health and Nutrition Examination Survey (KNHANES), 2007？2013. The population was divided into 2 groups according to body mass index (BMI) and waist circumference (WC). Blood mercury levels were analyzed using a gold amalgam collection method and categorized by interquartiles stratified by sex and occupational status(manual and non-manual workers). The study population was evaluated by Student’s t-tests, ？2 tests and logistic regression.

Results: A multiple logistic regression analysis after adjusting for all covariates showed that blood mercury levels were significantly associated with overweight and abdominal obesity in all subjects. According to BMI criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.92 (95% confidence interval [CI], 1.69？2.18) overall, 2.32 (95% CI, 1.93？2.80) in men, and 1.68 (95% CI, 1.42？1.99) in women. According to WC criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.97 (95% CI, 1.61？2.41) in men and 2.01 (95% CI, 1.69？2.40) in women compared with the lowest quartile. Additionally, a linear trend in overweight and abdominal obesity across increasing blood mercury levels was observed by P for trend test in multiple diagnostic criteria. After stratification by occupational status, the adjusted odds ratio of being in the highest blood mercury quartile was 2.06 (95% CI, 1.69？2.50) overall manual worker group, 2.42 (95% CI, 1.88？3.13) in men manual workers, and 1.86 (95% CI, 1.39？2.50) in women manual workers based on BMI categorize. According to WC criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 2.07 (95% CI, 1.56？2.74) in men and 2.37 (95% CI, 1.75？3.20) in women compared with the lowest quartile in manual worker group In non-manual worker group, the adjusted odds ratio of being in the highest blood mercury quartile was 1.95 (95% CI, 1.44？2.63) overall non-manual worker group, 3.02 (95% CI, 2.02？4.52) in men, and 1.54 (95% CI, 1.02？2.30) in women based on BMI categorize. According to WC criteria, the adjusted odds ratio of being in the highest blood mercury quartile was 1.93 (95% CI, 1.31？2.86) in men and 2.25 (95% CI, 1.41？3.59) in women compared with the lowest quartile in manual worker group

Conclusion: We found meaningful associations between blood mercury level and weight gain in a dose-dependent manner. Moreover, we attempted to stratify by occupation (manual and non-manual workers), which no study has done previously. A meaningful association of blood mercury and obesity was confirmed in some of these subgroups.