Background/aim Persistent organic pollutants (POPs) are man-made chemical compounds usually produced for agricultural and industrial applications, and possess notable toxicity potential and persistence, hence posing a threat to humans and the environment.

Exposure to POPs has been related to increased risk of some diseases such as diabetis and most recently, Metabolic Syndrome (MetS).

Methods Metabolic Syndrome is a group of risk factors characterised by central obesity, dyslipidemia, glucose intolerance and arterial hyperthension. The relationships between POPs and MetS are, however, not well established yet. Moreover, the relationships between POPs and lipid-related factors such as the body mass index (BMI) or blood cholesterol and tryglicerides can unmask the real associations between concentrations of POPs and MetS. Different statistical methodologies have been used to assess the relationships between exposure to POPs and MetS, including generalised linear modelling (GLM), environment-wide association studies (EWAS) and mediated models, a kind of structural equation modelling (SEM).

Results This research assesses the prevalence of Metabolic Syndrome in a Mediterranean general population (that of Catalonia, in Southern Europe, n=919) against a set of persistent organic pollutants, including organochlorine pesticides (OCPs), polychlorobiphenyls (PCBs) and polybromodiphenyl ethers (PBDEs), using several statistical approaches. The models were additionally adjusted by several covariates such as age, sex, social class, educational level, physical exercise, smoking habit and alcohol consumption. Alike GLM or EWAS, mediated models allowed to take into account mutual confounding effects between variables in both sides of the equation, including age, sex, the BMI and blood lipid content. Those variables had also an effect in the accumulation patterns of POPs in human populations.

Conclusion Using structural equation modelling, several organochlorine pesticides (including hexachlorobenzene, beta- and gamma-HCHs and 4,4’-DDE) and one polychlorobiphenyl (PCB-118) have been found to be strongly associated with Metabolic Syndrome. Also the OCPs alpha-HCH and 4,4’-DDT, and the PBDE congeners’ 66 and 71 have shown an association with MetS, but to a lower degree (90% of probability).