Pathways of micro- and nanoplastics transfer from plants to animals in the food chain

Plastic pollution has become a major global environmental challenge, with microplastics (MPs) and nanoplastics (NPs) increasingly detected in agricultural soils, water, sediments, and the atmosphere. Generated through the fragmentation and degradation of larger plastic materials as well as other sources, these particles can interact with co-contaminants, including heavy metals and persistent organic pollutants, and may alter environmental properties and biological processes. As primary producers, plants represent an important interface between environmental plastic contamination and food-web exposure. Current experimental evidence indicates that MPs and, particularly, NPs can be taken up by plants through roots and, under certain conditions, aerial tissues, with nanoscale particles generally showing greater potential for internalization and redistribution to above-ground tissues. However, the extent to which plant-associated plastics subsequently undergo trophic transfer to animals under environmentally realistic conditions remains less well established. Following ingestion, experimental studies indicate that NPs can cross biological barriers and reach tissues beyond the gastrointestinal tract, where exposure has been associated with oxidative stress, inflammatory responses, cellular effects, and alterations in physiological or behavioural endpoints in some model organisms. The relevance of these findings to environmentally realistic exposure levels and human health remains uncertain. This review critically synthesizes current evidence on the uptake and translocation of MPs and NPs in plants, their potential transfer to animals through terrestrial food chains, mechanisms governing their biological fate, analytical approaches for their detection and characterization, ecological and health implications, and current mitigation and policy perspectives. Particular emphasis is placed on distinguishing evidence of exposure and plant uptake from demonstrated trophic transfer, bioaccumulation, and biomagnification, while considering uncertainties associated with particle size, physicochemical properties, environmental conditions, and analytical limitations. Improving the characterization of these pathways through standardized methods, environmentally realistic field studies, and interdisciplinary research can strengthen environmental risk assessment and inform proportionate strategies for reducing plastic inputs and exposure across agricultural and terrestrial food systems.