Microplastics as Ecological Filters Across Food Systems: From Microbial Selection and Antimicrobial Resistance to Human Health Risks and Mechanisms

Abstract

Microplastics are increasingly detected throughout food-production systems, from agricultural soils and irrigation waters to aquaculture environments, food-processing facilities, and final food products. Beyond their role as contaminants and microbial carriers, plastic particles provide persistent surfaces for biofilm development and may selectively shape the microorganisms and functional traits that persist during environmental transport. This review introduces an ecological-filter framework for understanding how microplastics restructure microbial communities across food systems and how these processes may ultimately influence human exposure and health. We examine how polymer properties, conditioning films, weathering, environmental gradients, ecological succession, and colonization history drive plastisphere assembly and microbial turnover, with particular attention to pathogen selection, antimicrobial-resistance determinants, and horizontal gene transfer. We further distinguish three partially overlapping mechanisms through which foodborne microplastics may acquire human-health relevance: particle-mediated effects, arising from gastrointestinal interactions and changes in intestinal conditions and microbiota; chemical-mediated effects, involving compounds associated with or released from particles; and plastisphere-mediated effects, involving environmentally selected microorganisms or functional genes transferred through the food chain. Current evidence strongly supports dietary exposure, selective microbial and resistome restructuring, and several intermediate steps of biological transfer, while direct causal links between environmental plastisphere selection and human disease remain limited. We therefore propose that microplastics in food systems should be considered dynamic ecological filters and relays whose biological significance depends on their ecological history, microbial composition, functional traits, processing history, and interactions with the gastrointestinal environment. Integrating microbial ecology, multi-omics, cultivation, food-chain tracking, and mechanistic health assessment will be essential to determine when microplastic-associated ecological selection translates into meaningful human-health risk.