Relationship between serum concentrations of persistent organic pollutants and the prevalence of metabolic syndrome among non-diabetic adults: Results from the National Health and Nutrition Examination Survey 1999-2002

Aims/hypothesis: We recently reported associations of some persistent organic pollutants (POPs) with both prevalence of type 2 diabetes and insulin resistance in a US population with background exposure to POPs. Restricted to non-diabetic participants, we now investigate the relationship between POPs and the metabolic syndrome, a prediabetic state. Materials and methods: Cross-sectional associations were investigated in 721 non-diabetic participants aged ≥20 years. Nineteen POPs in five subclasses were selected because they were detectable in ≥60% of participants. Results: Among five POPs subclasses, organochlorine (OC) pesticides were most strongly and consistently associated with metabolic syndrome: adjusted odds ratios (ORs) of 1.0, 1.5, 2.3 and 5.3 across OC pesticide quartiles (p for trend <0.01). Dioxin-like polychlorinated biphenyls (PCBs) were also positively associated with adjusted ORs of 1.0, 1.1, 2.2 and 2.1 (p for trend = 0.01). However, non-dioxin-like PCBs showed an inverted U-shaped association with adjusted ORs of 1.0, 1.3, 1.8 and 1.0 (p for quadratic term <0.01). Associations of specific POPs varied across five components of the metabolic syndrome. OC pesticides were positively and significantly associated with four of the five components, especially elevated triacylglycerol and high fasting glucose, but not high blood pressure. PCBs were significantly associated with waist circumference, triacylglycerol and impaired fasting glucose. Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans showed small but significant associations only with high blood pressure. Conclusions/interpretation: This study suggests that the prevalence of a cluster of cardiovascular risk factors relates to background exposure to a mixture of POPs, several of which are also related to the prevalence of diabetes. POPs associated differentially with different components of the metabolic syndrome.