Superfund Research Program

December 2023

Hot Publication

Researchers at the University of Iowa SRP Center identified specific PCB compounds, or congeners, associated with diabetes risk. The authors also calculated the lowest concentration, known as threshold, that resulted in a biological change related to diabetes.

Although PCBs were phased out in 1978, the compounds can still be found in the environment and in old building materials and continue to be manufactured as byproducts of certain industrial processes. PCBs have been associated with a myriad of adverse health effects, including cancer and diabetes.

The team obtained data on PCB concentrations in serum and diabetes status from 1244 adults who participated in the National Health and Nutrition Examination Survey between 2002 and 2004. Then, they used a machine learning tool called decision tree analysis to identify PCB congeners and their thresholds associated with diabetes. Their analysis showed that PCB 126, at serum concentrations as low as 0.025 nanograms per gram, was the congener that was most consistently associated with diabetes.

Since people are often exposed to multiple PCB congeners at the same time, the scientists also estimated the combined associations of several serum PCB congeners with diabetes. They found that low levels of PCB 101 combined with high levels of PCB 126 decreased diabetes risk and that adding PCB 49 to the mixture increased the risk. The authors suggested that the metabolism of different PCBs may play a role in the interaction between PCB mixtures and diabetes.

According to the research team, these findings provide new insights into the combined association of PCBs and diabetes. However, further research to reveal the mechanisms of disease development is needed.

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