Can maternal microplastic exposure affect the breast milk microbiome in animal research?

What is actually in it

Microplastics are plastic fragments smaller than 5 millimeters. Polystyrene microplastics come from polystyrene plastic as it breaks down.

Plastic particles can come from packaging, synthetic fibers, dust, and worn plastic products. You cannot avoid them completely, but you can reduce some daily contact.

What the research says

A 2026 FASEB Journal mouse study exposed pregnant and lactating dams to polystyrene microplastics in drinking water.

The study found changes in both the milk microbiome and offspring gut microbiome. Beneficial bacteria such as Ligilactobacillus decreased, while bacteria such as Escherichia-Shigella increased. Offspring also showed impaired immune development markers, including lower serum interleukin-6, lower splenic T-cell proportions, and weaker intestinal barrier integrity.

This is animal evidence, not proof of harm in human breastfeeding. The practical takeaway is gentle: keep breastfeeding guidance with your clinician, and reduce avoidable plastic and synthetic fiber contact where it is easy. For baby items that touch skin every day, organic cotton can reduce synthetic textile shedding.