Association between Concurrent Exposure to Dioxin and Mercury and Metabolic Syndrome in an Endemic Area in Taiwan

Abstract

Introduction: Both dioxin and mercury are related to the development of metabolic syndrome (MetS). However, studies on the effect of concurrent to dioxin and mercury on metabolic syndrome are limited. We conducted a study in Taiwan to evaluate the effect in an endemic area where resident were exposed to both polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and mercury released from a factory.Methods: We recruited participants from residents in the endemic area and defined serum PCDD/Fs levels ≥20 pg WHO98-TEQDF/g lipid and mercury levels >20 ppb as high exposure mercury levels. MetS was defined as meeting three of the following: fasting glucose ≥100 mg/dL or under treatment for diabetes, waist circumference ≥90 cm in men or ≥80 cm in women, triglycerides ≥150 mg/dL or under treatment for elevated triglycerides, high-density lipoprotein <40 mg/dL in men or <50 mg/dL in women, and blood pressures ≥130/85 mmHg or under treatment for hypertension. Uric acid ≥ 7 mg/dl was defined as high level. Results: In the 2758 participants, 785 patients of MetS were identified. We observed positive associations of both high dioxin level and high mercury level with MetS. After adjusting for sex, uric acid, and age, we found high dioxin levels (adjusted odds ratio [AOR] =1.39, 95% confidence interval [CI]: 1.12-1.73), high mercury levels (AOR =1.59, 95% CI: 1.14-2.23), older age (AOR = 2.81, 95% CI: 2.21-3.582 for 40-64 year and AOR = 4.57, 95% CI: 3.42-6.10 for age ≥ 65 year), and high uric acid levels (AOR =2.31, 95% CI: 1.87-2.87) were independent predictors for MetS.Conclusions: Both exposures to PCDD/Fs and to mercury were associated with MetS, independent of age and uric acid.