Microplastics as benzo-a-pyrene carriers: genotoxicity assessment simulating human gastric digestion

Microplastic particles (MPs) are ubiquitous environmental pollutants that can remain in ecosystems for prolonged periods. Plastic materials undergo various degradation processes driven by chemical, physical, and biological factors that alter their size, shape, composition, and bioavailability. The gastrointestinal tract is the primary pathway through which MPs are absorbed, raising concerns as they can transport harmful pollutants and microorganisms into the body. Despite their widespread presence, the effects of exposure to MPs that vehicle environmental toxins are still not well understood. In this study, we rigorously simulated the photoaging processes of polystyrene MPs of two distinct sizes (1 µm and 5 µm) and confirmed their capacity to adsorb benzo[a]pyrene, a known carcinogen. Moreover, we explored the transport capabilities of these MPs and analyzed their genotoxic effects on liver cells under simulated gastric digestion conditions. Our findings reveal that MPs enriched with BaP release this toxic compound when ingested and exposed to gastric juices, markedly increasing their toxicity compared to the individual components. This research underscores the alarming potential of MPs to exacerbate risks associated with environmental pollutants in human health.