Associations of prenatal exposure to polybrominated diphenyl ethers and polychlorinated biphenyls with long-term gut microbiome structure: a pilot study

The gut microbiome is influenced by early-life exposures, but—despite potentially enormous implications for child health—is understudied in environmental epidemiology. This pilot study is one of the first to explore in utero exposures and long-term gut microbiome profiles. We examined the association between exposure to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) during pregnancy and the mid-childhood gut microbiome. METHODS: We measured levels of PBDE-47, PBDE-99, PBDE-100, and PBDE-153 and PCB-138, PCB-153, and PCB-180 in maternal plasma during early pregnancy (n = 18) and at delivery (n = 25) in women of European descent who breastfed the child participant of the Gestation and Environment cohort in Sherbrooke, Québec (recruited 2007–2009). Bacteria in the mid-childhood (6–8 years) fecal microbiome were detected with 16S rRNA sequencing. To test for differences at the taxon level, we used the Microbiome Comprehensive Association Mapping algorithm. RESULTS: Early pregnancy PCB-153, PCB-180, and the sum of PCBs (Σ(3)PCB) concentrations were associated with a higher relative abundance of Propionibacteriales and Propionibacteriaceae in mid-childhood. Higher PCB-180 and Σ(3)PCB were associated with higher relative abundance of Bacillales Family XI. Higher PBDE-99 exposure was associated with a decrease in uncultured bacteria within the Ruminococcaceae NK4A214 group and PBDE-47 was associated with differences in Ruminococcus 2. These taxon-level changes did not result in differences within- or between-subject diversity. Exposures at delivery were not associated with differences in taxa. CONCLUSIONS: Prenatal exposure to PCBs and PBDEs is associated with mid-childhood gut microbiome profiles. Larger studies are needed to confirm these results and explore health implications.