Störmer et al.
10.3389/fchem.2024.1397913
approaches published in the scienti fi c literature; and (iii) explain and critically discuss the presented test methods and approaches concerning their objectives, potentials, and limitations. The overarching intention is to identify and highlight the resulting conclusions for future research toward a better harmonized rule- and science-based evaluation scheme for paper-based food contact materials. This paper focuses on simulating the transfer processes to food. Work about methods to detect and identify possibly migrating substances as well as bioassays, although belonging to the area of new alternative approaches, are intentionally excluded from this review.
with functional barriers like inner bags, barrier coatings, or in direct contact for packing insensitive foods like salt (Biedermann and Grob, 2013; Geueke et al., 2018). In contrast to plastic food contact materials (FCM), which are subject to a speci fi c and detailed EU legislation (EU, 2023) in a systematic and largely science-based way, paper-based food contact materials still lack such detailed speci fi c regulations at a harmonized European level (Simoneau et al., 2016). One major reason is that for paper, due to the inherent structural and chemical compositional complexity, the knowledge base for proper risk assessment is not as advanced as it is for plastics. Nevertheless, the safety of paper applications in food contact needs to be ensured e.g., in the European Union according to Article 3 of the Framework Regulation 1935/2004 (EU, 2004). Generally, the transfer of substances from packaging materials to foods must be evaluated to ensure consumer safety and this at best, as realistic scenarios. However, to cover a large number of possible foods as fi lling goods and avoid analytical dif fi culties with complex food matrices, simulants and standardized contact conditions are typically used. Food contact compliance testing and safety evaluation of paper are still largely based on standard methods, which are rather conventional test procedures than simulating transfer to real foods. A systematic and holistic approach similar to plastic food contact materials is still missing but would be needed as a basis for the future EU legislation and framing better rules for the paper packaging industry (Lestido-Cardama et al., 2020; Kourkopoulos et al., 2022). The requirements to ensure consumer safety in food contact applications have been advancing during the last few decades, especially with non-intentionally added substances emerging to the forefront (Koster et al., 2015; Leeman and Krul, 2015; EP, 2016; CoE, 2020; Nerin et al., 2022). Paper food contact materials have been reported in a multitude of scienti fi c articles as potential sources for releasing/migrating chemical contaminants of known and unknown identity and toxicity into the foods when in contact with them. In particular, food contact materials having recycled paper qualities raise concerns (Jickells et al., 2005; Sturaro et al., 2006; Begley et al., 2008; Zhang et al., 2008; Gärtner et al., 2009; Vollmer et al., 2011; EFSA, 2012a; Pivnenko et al., 2015; Canavar et al., 2018; Deshwal et al., 2019; Conchione et al., 2020; Zabaleta et al., 2020; Pan et al., 2021). Substances with only scarce or no toxicological data can be evaluated as safe only at low migration limits, e.g., by applying Threshold of Toxicological Concern (EFSA, 2012b; CoE, 2020). Test methods — which highly overestimate real migration into foods — may trigger either premature negative evaluations and unjusti fi ed non-compliance assessments of paper materials or the need for elaborate and costly migration tests in contact with representative or worst-case foodstuffs themselves ( “ food prevails ” ). This risk usually increases with decreasing migration limits. Overall, there is a high number and variability of applicable tests and evaluation methods in Europe. There is a lot of discussion in the scienti fi c literature, which methods to apply for various purposes, and the related uncertainties and interpretation gaps. The objective of this article is to (i) provide an overview of available, legally binding, and normative test procedures, including guidance documents in Europe; (ii) compile alternative scienti fi c
2 A short view on the diversity of paper food contact applications
Paper is commonly used as a packaging material for a wide range of food products, including dry goods (e.g., fl our, cereals, snacks, and pasta), baked goods (e.g., bread and pastries), and fresh produce (e.g., fruits and vegetables). Important products for food protection during transport and storage are bags, boxes, and trays. For high- temperature applications, e.g., baking, parchment paper or baking cups for muf fi ns are used to prevent food from sticking to surfaces in commercial and home baking settings and tea bags or coffee fi lters for hot aqueous contact. In food service areas within the commercial and residential settings, disposable tableware — such as cups, plates, bowls, napkins, and straws — is made from paper. Other applications comprise wrapping materials — including waxed paper — for a variety of food products, such as meat products and sandwiches. Paper can be used as it is or coated with a variety of barrier materials to prevent moisture, oxygen, and aroma compounds from entering or leaving the package and improve grease resistance. Barriers might be coextruded fi lms (e.g., polyethylene), lacquers, or coatings from petrochemical or biobased sources. Finally, labels and tags — applied to food packages or food products for identi fi cation or promotional purposes — are often based on paper. A comprehensive overview of paper categories and paper-based food packaging materials can be found in the literature (Simoneau et al., 2016; Deshwal et al., 2019). In conclusion, the use of paper is highly diverse, covering a wide range of products and food contact applications. The paper types and designs depend on the particular application needs and the relevant regulatory standards. Demonstrating or proving the chemical safety of such large variety of applications pose a serious challenge to industrial, contract, and control laboratories, particularly when recycled fi bers carrying potentially numerous chemical contaminants enter production lines. Undoubtedly, this situation indicates a need for better science-based methodological support toward the safety assessment of paper food contact materials, as indicated by Grob (2022).
3 EU legislation of fi ber-based food contact materials and related (supra) national provisions
As with any other food contact material, paper for food contact is subject to the overarching European Framework Regulation (EC)
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