Environmental Fate of Micro- and Nanoplastics through Aging, Vector Effects, and Management Strategies

Abstract Micro- and nanoplastics (MNPs) are now recognised as globally pervasive contaminants whose environmental risks are not fixed at the point of release but evolve continuously through aging. Once in the environment, MNPs undergo photodegradation, oxidation, mechanical fragmentation, thermal alteration, and biofouling processes that progressively transform particle size, surface chemistry, morphology, density, and reactivity in ways that fundamentally alter transport, bioavailability, and ecological interactions. Critically, aging converts initially inert particles into dynamic contaminant vectors capable of acquiring, transporting, and releasing metals, hydrophobic organic contaminants, pharmaceuticals, pathogens, and antibiotic resistance determinants across environmental compartments. Despite substantial research on MNP occurrence and toxicity, a major gap persists: aging, transport, vector behavior, and management are routinely studied as isolated processes, preventing an integrated understanding of how MNPs evolve from source to receptor. This review addresses that gap by establishing a unified source-aging-transformation-fate-vector-risk-management continuum grounded in field-realistic conditions rather than pristine-particle assumptions. We critically synthesize current knowledge on MNP sources, compartment-specific aging dynamics, physicochemical transformations, ecological and human health risks, analytical challenges, and management strategies with explicit emphasis on how aging-induced changes propagate through each domain. Key findings indicate that pristine MNP properties systematically underestimate field risks; that aged secondary nanoplastics represent an insufficiently regulated contaminant class; and that effective management must account for aging-modified particle behavior at every stage from source reduction to treatment and end-of-life. Integrating the full source−aging−transformation−fate−vector−risk−management continuum into environmental risk assessment is essential for developing predictive, realistic, and sustainable approaches to MNP pollution control.