Long-term exposure to food-contact microplastics disrupts gut microbiota and alters colon metabolites.

Microplastics (MPs) are increasingly recognized as widespread contaminants, and the impact of long-term exposure to different types of MPs on colon damage is poorly explored. The effects of four food-contact MPs (polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET)) on colon were investigated in a mouse model. The results indicated that the four MPs could reduce colon length and index, increased oxidative stress, but did not trigger inflammatory responses. 16S rRNA gene sequencing showed that α-diversity remained stable, but β-diversity analysis revealed significant microbial shifts. The potential mediators of the damage effects included Alistipes, Odoribacter, and Parabacteroides for PS; Litchfieldia for PP; Dubosiella, Turicibacter, and Muribaculum for PE; and Bifidobacterium for PET. Metabolomics revealed MP-specific metabolic disturbances, with PS causing the most severe perturbations by affecting protein digestion and neurotransmitter pathways, whereas PET exhibited minimal changes. These findings provided critical insights for risk assessment of food-contact MPs.