Early exposure to toxic TCDF messes with gut bacteria later in life, finds study in mice

By Shannon Kelleher

Early-in-life exposure to a common toxic chemical found in some foods and in breastmilk may disrupt healthy bacteria in the gut and increase a person’s risk for developing various diseases later in life, according to a new animal study.

The findings, published Aug. 14 in the journal Environmental Health Perspectives, may shed light on the link between childhood exposure to persistent organic pollutants (POPs) and widespread obesity and diabetes in adults, according to the authors.  

More than 460 million people worldwide have diabetes, while global obesity levels have tripled since 1975. One in three US adults and one in six children are considered obese, according to a 2023 report. 

“This study emphasizes the importance of the microbiome as a key target of early life environmental pollutant exposure,” the paper states. Exposure to the children can occur before birth when pregnant women are exposed to the chemicals as well as after birth through breastfeeding.  

Although previous research has identified correlations between exposure to POPs and obesity and type 2 diabetes, the microbiome’s role has not been clear, according to the study.

The researchers fed infant mice pills containing the chemical 2,3,7,8-tetrachlorodibenzofuran (TCDF) for five days, collecting data on their gut microbiomes right after the mice were fed the last dose and again three months later, when they had reached young adulthood. Compared to a control group that was not fed TCDF, the mice had higher body weight and glucose intolerance – a hallmark of diabetes – long after they ingested the chemical.

The researchers also measured lower levels of two bacteria species important for gut health in the mice fed TCDF when they were four months old, as well as markers of immune problems and inflammation in the intestines.