Micro- and nanoplastics (MNPs) in liquid food: From occurrence, health risks and migration mechanisms to AI-enabled analytical and circular solutions

Microplastics (MPs, 1 μm-5 mm) and nanoplastics (NPs, <1 μm) are routinely detected in wide array of liquid food, including drinking water, milk, beverages and seasonings. Reported concentrations span approximately 1 to 10 particles per liter, reflecting major differences in analytical methods and the complexity of food matrices. These findings highlight liquid food as an important but underrecognized exposure pathway. Despite significant analytical challenges, particularly the optical diffraction limit and matrix-induced interference, continue to hinder quantification of NPs, toxicological studies indicate that ingested micro- and nanoplastics (MNPs) can impair intestinal barrier integrity and induce inflammatory responses. This review synthesizes current knowledge on the occurrence, migration mechanisms and exposure implications of MNPs in liquid food, focusing on food-contact materials as primary source. We propose that migration is not only by mechanical abrasion and polymer degradation but also by physicochemical partitioning at the food-packaging interface (Nernst partition law). Even biodegradable polymers, such as PLA, often assume safer material, can fragment rapidly, contributing substantially to MNP pollution. We further evaluate current pretreatment and analytical techniques, highlighting how machine learning (ML) and deep learning (DL) are enhancing detection and classification efficiency. While ML/DL applications in analytical detection are gaining validation in liquid, their potential in recycling optimization and predictive migration modeling remains conceptual. Ultimately, this review identifies key scientific and regulatory priorities, including the development of safer packaging, refined exposure assessment, deeper understanding migration mechanisms and mitigating MNP contamination into liquid food.