Foodborne pathogens in the plastisphere: Can microplastics in the food chain threaten microbial food safety?

Microplastics (MPs) contaminate the global marine and terrestrial ecosystems. This environmental contamination can enter the food chain, with MPs found in drinking water, fishery products and other food categories. Consequently, ingestion is considered the main route of human exposure to MPs. Concerns exist on the potential of MPs to act as vectors for pathogenic bacteria, possibly threatening microbial food safety. Starting from the current evidence on foodborne pathogens associated with MPs, we review the state of knowledge on the putative role of MPs in enhancing harmful bacterial traits and transporting them to humans. Finally, we focus on the simultaneous uptake of MPs and pathogens in the human gut. Overall, we identify major knowledge gaps, both on the mechanisms and the possible health outcomes. The scarce and inconclusive results regarding the effect of MPs on microbial virulence and evolution, together with the insufficient knowledge about the attachment of microbial toxins to MPs, highlight the need for further studies. We conclude that biofilm-coated MPs in foodstuffs may pose several risks to food safety, but further research will be essential to determine the extent of their effect on human health.