Differential Effects of Four Food-Contact Microplastics on Colonic Health, Gut Microbiota, and the Fecal Metabolome in Mice.

BACKGROUND

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.

OBJECTIVES

The effects of 4 food-contact MPs [polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET)] on the colon were investigated in a mouse model.

METHODS

Mice were exposed to PE, PP, PS, or PET at 25 mg/kg body weight (b.w.)/d for 6 wk. Colonic oxidative stress and inflammation were evaluated, and gut microbial composition and fecal metabolic profiles were analyzed using 16S rRNA gene sequencing and untargeted metabolomics, respectively.

RESULTS

The results indicated that the 4 MPs could reduce colon length and index, increase 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.

CONCLUSIONS

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.