Mixed exposure to dioxins and dioxin-like PCBs may increase risk of obesity: Study

A new study published in The Journal of Clinical Endocrinology & Metabolism showed that adult obesity risk is substantially elevated when dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are combined, with 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) contributing the most. 

There is insufficient data to support the idea that dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) have conflicting effects on obesity. Prior studies have indicated possible connections between obesity and dioxins or DL-PCBs. It is yet unknown how dioxins and DL-PCBs work together to cause obesity. Thus, Zhao-Xing Gao and colleagues carried out this investigation to provide a tangible link between dioxin elements and adult obesity.

According to recent research, environmental pollutants that alter hormones, including dioxins and dioxin-like polychlorinated biphenyls, may raise the risk of obesity. This research used data from the National Health and Nutrition Examination Survey from 2003 to 2004 to assess the association between obesity or obesity indices and combined exposure to 9 different kinds of dioxins and DL-PCBs in 852 individuals.

9 compounds were selected for analysis, which were PCB28, PCB66, PCB74, PCB105, PCB118, PCB156, 1,2,3,4,6,7,8,9-HpCDD; 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) and 3,3',4,4',5-pentachlorodibenzofuran (PnCB). Of all the subjects, 34% had general obesity and 53.9% had abdominal obesity. A variety of statistical techniques were used to assess the relationship between DL-PCB and dioxin exposures and obesity. To evaluate the possible contribution of A1c to this connection, mediation analysis was conducted.

A single exposure to elevated levels of HpCDD, OCDD, PnCB, PCB74, PCB105, and PCB118 was linked to a greater risk of both general and abdominal obesity, according to multivariable logistic regression analysis. All chemicals, with the exception of PCB28, PCB74, PCB66, and PCB156, were associated with an elevated risk of abdominal and general obesity in both men and women, according to a stratified analysis by sex.

The risk for obesity was strongly correlated with both dioxin and DL-PCB exposure, with HpCDD contributing the most. OCDD, HpCDD, PnCB, PCB74, PCB105, and PCB118 were substantially correlated with waist circumference and body mass index when obesity indicators were taken into account. With mediation ratios of 6.94% for general obesity and 5.21% for abdominal obesity, A1c levels substantially mediated the relationship between mixed exposure to dioxins and DL-PCBs and obesity. Overall, these results showed that DL-PCBs and dioxins could be separate risk factors for obesity.

Reference:

Gao, Z.-X., Zhang, P., Xu, S.-Z., He, Y.-S., Hu, X., Ge, M., Xu, Y.-Q., He, T., Wang, P., & Pan, H.-F. (2024). Association Between Mixed Exposure to Dioxins and Dioxin-Like Polychlorinated Biphenyls and Obesity Among US Adults. In The Journal of Clinical Endocrinology & Metabolism. The Endocrine Society. https://doi.org/10.1210/clinem/dgae873