Microplastics (MPs) have emerged as pervasive contaminants in marine ecosystems, posing escalating ecotoxicological risks across trophic levels. This review highlights the current knowledge on the sources, types, and mechanistic pathways of MPs toxicity by assessing their environmental uptake, trophic transfer, and associated impacts on aquatic organisms and human health. Previous studies collectively demonstrate that integrated field assessments, chemical characterization, and advanced multi-omics methodologies provide a holistic understanding of polymeric particle bioavailability, transport pathways, and cellular interactions across diverse marine species, ranging from primary producers to higher trophic level apex consumers. In this review, modeling and spatial analyses further elucidate the transport processes and distribution patterns of MPs within marine ecosystems. Prior studies have shown that MPs ingestion alters nutrient absorption, enzymatic efficiency, and redox homeostasis in marine organisms, triggering oxidative stress, metabolic disruption, and sub-lethal physiological impairments across multiple trophic levels. Recent evidence reveals that MPs can be translocated through pelagic and benthic food webs and may facilitate the transfer of sorbed contaminants and additives across trophic levels. Reviews of molecular or histopathological data show MPs trigger inflammatory responses, oxidative damage, apoptosis, genotoxicity, and immunity alterations in marine species. Review studies evaluate nanoremediation, biochar amendment, and engineered carbonaceous sorbents as key mitigation strategies against MPs risks. Probabilistic risk assessments underscore substantial human dietary exposure through seafood, policy integration, urging integration of MPs monitoring into global marine health frameworks for proactive intervention. These reviewed insights enhance mechanistic MPs ecotoxicology knowledge, underpinning sustainable strategies and policies for marine biodiversity protection and human well-being security.
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