## 3 Studied Polymers and Food Contact Materials  
The research articles summarized in Table 1 examine a diverse range of polymeric matrices employed in FCMs, including conventional and recycled plastics, emerging biodegradable materials, as well as composite systems that incorporate multilayer structures, adhesives, or coatings. This diversity reflects both current trends in FCM production and key areas of regulatory and toxicological concern. While not exhaustive, the polymer types covered are representative of materials with high market prevalence and/or growing relevance due to sustainability goals (e.g., recycled and bio-based plastics), thereby including substances most likely to contribute to consumer exposure. Polyethylene terephthalate (PET) is among the most frequently studied polymers, with investigations including virgin and recycled PET (rPET) in bottled water [24], microwave containers [25], and beverage bottles [39]. The prevalence of PET in single-use packaging drives research into its oligomer migration, particularly cyclic and linear terephthalate derivatives [59], with studies emphasizing rPET due to concerns over contaminants introduced during reprocessing [62]. Similarly, polyethylene (PE), including high-density PE (HDPE), low-density PE (LDPE), and recycled PE (rPE) and LDPE (rLDPE), has been extensively examined in films, reusable bottles, and multilayer packaging [50; 64; 67]. These studies often focus on antioxidant degradation products, plasticizers like phthalates, and hydrocarbon oligomers, highlighting the susceptibility of the material to releasing NIAS under thermal stress as a consequence of recycling processes [18; 42]. However, the ability of current NTA methodologies to fully capture NIAS arising from recycling remains limited due to the higher complexity and variability of recycled matrices, the presence of trace-level contaminants from previous use cycles, and the lack of comprehensive spectral libraries or reference standards for unknown degradation or contamination products. Polypropylene (PP) is another widely analyzed polymer, featured in food storage containers, baby bottles, and microwave trays [35; 43; 54]. Its applications at high temperatures, such as microwave heating or dishwashing, have prompted investigations into additive degradation and the formation of volatile aldehydes or phenolic compounds [36; 54]. Recycled PP (rPP) has also been scrutinized for contaminants arising from post-consumer waste, including odoriferous hydrocarbons and surfactant residues [48]. These findings underscore the need for advanced analytical methods to address the complexity of NIAS in recycled FCMs. Biopolymers, such as polylactic acid (PLA) and polyester (PES) mixtures, represent an emerging focus as a result of their growing use as eco-friendly alternatives. Studies on PLA-based films and pellets reveal cyclic lactic oligomers and adipate derivatives as predominant migrants, with migration tests simulating both aqueous and fatty food conditions [6; 60; 61]. Epoxy-based coatings, commonly applied to metal cans, have been extensively evaluated for NIAS derived from resin precursors like bisphenol derivatives, such as Bisphenol A diglycidyl ether (BADGE), and their reaction byproducts [40; 41]. These coatings, which are designed for durability, can potentially release complex oligomers and phenolic compounds under migration conditions [38]. Similarly, polyurethane (PUR) and polyester-phenolic coatings in metallic FCMs have been linked to isocyanate and cyclic oligomer migration, underscoring the challenges of identifying reactive intermediates in polymer matrices [44; 45; 55]. Kitchenware and reusable food utensils, which are often fabricated from polyamide (PA), polybutylene terephthalate (PBT), or melamine-formaldehyde resins, have been studied for their migration of monomers, plasticizers, and oligomers under simulated cooking conditions [21; 33; 34].