Hidden Threats in Food Systems: Unveiling Metal Contamination through Microplastic-Mediated Trophic Transfer

Abstract

Microplastics (MPs) and heavy metals (HMs) have emerged as pervasive and co-occurring contaminants in aquatic ecosystems, posing escalating threats to environmental integrity, food security, and public health. This review synthesizes current knowledge on the sources, environmental distribution, interactions, bioaccumulation, and trophic transfer of MPs and HMs within aquatic food webs. Evidence indicates that MPs function not only as persistent pollutants but also as highly effective vectors for metal adsorption, transport, and release, altering metal speciation, bioavailability, and toxicity. Across multiple trophic levels, from plankton and benthic organisms to fish and apex predators, MP–metal interactions facilitate contaminant uptake, enhance trophic transfer, and increase internal exposure burdens. Mechanistic studies reveal that these complexes induce oxidative stress, inflammatory responses, cellular damage, and genotoxicity through adsorption–desorption dynamics and biological membrane interactions. Advances in spectroscopic and analytical techniques have improved contaminant detection; however, significant challenges remain regarding methodological standardization, quantification accuracy, and nanoplastic characterization. Current evidence suggests that seafood consumption represents a major pathway of human exposure, raising concerns about chronic health effects. Addressing critical knowledge gaps through harmonized methodologies, improved monitoring tools, and integrated risk assessment frameworks is essential for developing effective mitigation strategies and safeguarding aquatic ecosystems and human health.