Can PFAS exposure through breast milk affect a baby's gut bacteria and brain development?

What's actually in it

Breast milk is the gold standard for infant nutrition, but it also carries chemical contaminants that accumulate in a mother's body. PFAS are among them. These chemicals dissolve into breast milk from the mother's blood, and babies consume them at every feeding during a critical developmental window.

The infant gut microbiome is being established during the first months of life. The bacteria that colonize a baby's gut influence digestion, immune development, and even brain function through the gut-brain axis.

What the research says

A 2025 study in J Hazard Mater measured PFAS levels in breast milk and then analyzed the gut microbiota of the breastfed infants. The researchers also assessed infant neurodevelopment to see if changes in gut bacteria mediated effects on the brain.

Higher PFAS levels in breast milk were linked to altered gut microbial composition in infants. Certain beneficial bacteria were reduced while others increased. These shifts in gut bacteria partially mediated the association between PFAS and neurodevelopmental scores.

This doesn't mean you should stop breastfeeding. The benefits of breast milk far outweigh the risks from PFAS contamination. But it does highlight the importance of reducing PFAS in the environment so less ends up in breast milk in the first place.

Mothers can reduce their own PFAS exposure by filtering drinking water, avoiding nonstick cookware, and choosing PFAS-free food packaging. These changes take time to lower body levels, so starting before or early in pregnancy is ideal.