Evidence of a positive association between dietary exposure to polychlorinated biphenyl (PCB) and weight gain among women in the E3N prospective cohort

Background: Polychlorinated biphenyls (PCB) and dioxins are persistent organic pollutants found in food and known for their ability to bioaccumulate. Various animal studies have highlighted obesogenic effects related to the exposure to PCB and dioxins, nevertheless human studies have led to inconsistent results. The present study aims to investigate the associations between dietary intakes of PCB and dioxins and the risk of weight gain, overweight and obesity in the French E3N cohort (Étude Épidémiologique auprès de femmes de la mutuelle générale de l'Éducation Nationale). Methods: The present study included 63,758 women with a mean age of 52.9 years, who completed a food frequency questionnaire in 1993 and were followed for 23 years. Dietary intakes to the sum of dioxins and dioxin-like PCB (DL-PCB) and to non-dioxin-like PCB (NDL-PCB) were estimated using food consumption data combined with food contamination levels from the French Agency for Food, Environmental and Occupational Health and Safety (ANSES). Adjusted Cox proportional hazard models were used to estimate hazard ratios (HR) and their 95 % confidence intervals for the risk of obesity, overweight and weight gain >10 kg during follow-up. Results: Our results suggest a positive and linear association between dietary intakes of dioxins + DL-PCB and intakes of NDL-PCB and the risk of weight gain (HRdioxins+DL-PCB = 1.07 (1.05–1.1), HRNDL-PCB = 1.08 (1.06–1.1)), overweight (HRdioxins+DL-PCB = 1.03 (1.01–1.05), HRNDL-PCB = 1.05 (1.03–1.06)), and obesity (HRdioxins+DL-PCB = 1.08 (1.04–1.12), HRNDL-PCB = 1.09 (1.06–1.12)). In sensitivity analyses adjusting for diet, the association between dioxins + DL-PCB dietary intake and obesity was no longer observed. Results remained unchanged or were attenuated but still significant regarding the association between dietary intake of NDL-PCB and obesity risk in all sensitivity analyses. Similar results were observed for the risks of weight gain and overweight. Discussion: This study suggests a positive and linear association between dietary intakes of NDL-PCB and the risk of obesity, a major risk factor for most non communicable diseases. Further studies are needed to confirm these results in other populations and to better understand the biological mechanisms underlying this association. © 2024 Elsevier B.V.