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Persistent organic pollutants contribute to metabolic dysfunction, regardless of weight status
Adults with and without obesity who had at least two cardiometabolic abnormalities were more likely to have higher serum concentrations of persistent organic pollutants vs. those considered metabolically healthy, according to findings published in the American Journal of Epidemiology.
“To the extent that clinicians care about the etiopathogenesis of the metabolic disorders they treat, our study is clinically relevant,” Miquel Porta, MD, MPH, PhD, professor at Hospital del Mar Institute of Medical Research and School of Medicine, Universitat Autonoma de Barcelona, Spain, told Endocrine Today. “It sheds light on the pathophysiology of metabolic health, and on some widespread exposures to persistent organic pollutants that contribute to metabolic disorders.”
Porta and colleagues analyzed data from 860 adults participating in the 2002 Catalan Health Interview Survey (mean age, 45 years; 56.4% women; mean BMI, 26.5 kg/m²; mean waist circumference, 87 cm). Participants completed a physical exam and interview and provided blood and urine samples. Researchers classified participants as having an unhealthy metabolic phenotype if they had two or more of the following cardiometabolic abnormalities: hypertension; hypertriglyceridemia; HDL cholesterol 40 mg/dL or lower in men or 50 mg/dL or lower in women; fasting plasma glucose at least 100 mg/dL or a diagnosis of diabetes; insulin resistance, defined as homeostatic model of assessment of insulin resistance (HOMA-IR) of at least 4.66; and systemic inflammation, measured by a high-sensitivity C-reactive protein level of at least 7.35 mg/dL. Metabolic syndrome was determined according to International Diabetes Federation (IDF) criteria. Researchers measured serum concentrations of eight persistent organic pollutants that were above the detection limit in at least 85% of participants, and used general linear regression models to assess the relationship between the number of cardiometabolic abnormalities (as a continuous variable) and concentrations of persistent organic pollutants.
Within the cohort, 56.2% of participants were considered metabolically healthy; among those, 4.5% had obesity and 17.6% had overweight, whereas 8.3% had normal weight but were considered metabolically unhealthy, according to researchers.
Researchers found that concentrations of the persistent organic pollutants hexachlorobenzene (HCB), betahexachlorocyclohexane (HCH) and polychlorinated biphenyls (PCBs) were associated with both the unhealthy metabolic phenotype and metabolic syndrome, after adjusting for BMI and other confounders. Among normal-weight adults, concentrations of the four PCBs 118, 138, 153 and 180 were associated with an unhealthy metabolic phenotype. Normal-weight adults in the third quartile of combined PCB concentrations had a threefold greater risk for having an unhealthy metabolic phenotype vs. those in the lowest quartile (95% CI, 1.4-6.3). Participants with overweight or obesity in the upper quartiles of PCB concentrations were also more likely to have an unhealthy metabolic phenotype vs. those in the lowest quartile; prevalence ratios in the upper quartiles of PCBs ranged from 1.2 to 1.4 (P for trend < .005).
Researchers also found that concentrations of HCB were associated with metabolic syndrome; the risk for having metabolic syndrome as defined by IDF or National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) criteria was 2.7 and 2.8 times higher, respectively, for those with HCB concentrations in the highest vs. the lowest quartile; HCH and all four PCB concentrations were also associated with at least one definition of metabolic syndrome, according to researchers. Results persisted in sensitivity analyses that excluded participants with type 2 diabetes.
“It is true that individual patients and clinicians can only modestly change persistent organic pollutant concentrations in patients,” Porta said. “However, individual habits play a role, and so do public and private policies; ie, government and corporate policies shown to decrease ‘internal contamination’ and body concentrations of persistent organic pollutants.”
The findings add to the existing evidence supporting policies to decrease human exposure to persistent organic pollutants, Porta said, adding that for many in the general population, persistent organic pollutant exposure occurs largely through the ingestion of fatty parts of animal foods.
“Although persistent organic pollutant exposure is a systemic issue — it has many causes and many effects — we cannot stay paralyzed,” Porta said. “We have and we can act.” – by Regina Schaffer
For more information:
Miquel Porta, MD, MPH, PhD, can be reached at Hospital del Mar Institute of Medical Research and School of Medicine, Universitat Autonoma de Barcelona, Carrer del Dr. Aiguader 88, E-08003, Barcelona, Spain; email: mporta@imim.es.
Disclosures: The researchers report no relevant financial disclosures.