Interactions between polystyrene-derived micro- and nanoplastics and the microbiota: a systematic review of...

Micro- and nanoplastics (MNPs), especially polystyrene-derived particles (PS-MPs/PS-NPs), have become a growing concern due to their increasing presence in the environment and their proven biological toxicity. Although PS particles have been identified in various human tissues, including feces, placenta, and blood, their impact on the gut microbiota and microbiota-driven metabolic pathways remains insufficiently synthesized. This systematic review aims to compile current in vivo evidence from mouse studies to assess how PS-MP/NP exposure influences gut microbial diversity, taxonomic composition, microbial metabolites, and subsequent physiological outcomes. A PRISMA-guided literature search identified 15 controlled mouse studies published between 2010 and 2024. Across these studies, PS exposure consistently induced gut dysbiosis, characterized by reductions or shifts in alpha-diversity, distinct beta-diversity clustering, loss of beneficial commensals such as Lactobacillus, Bifidobacterium, and members of Ruminococcaceae, and enrichment of opportunistic or pro-inflammatory taxa including Proteobacteria, Helicobacter, and Staphylococcus. Notably, MNPs particles induced more pronounced microbial disruption than micro-sized forms. Overall, current experimental evidence indicates that PS-MPs/PS-NPs induce multidimensional toxicity by simultaneously disrupting gut microbial ecology and host metabolic pathways. These findings emphasize the need for standardized methodologies in microplastic research and highlight the importance of clarifying the long-term health effects of human exposure to micro- and nanoplastics.