Störmer et al.
10.3389/fchem.2024.1397913
simulating the transfer, conventional procedures are usually applied, which shall cover the worst case (BfR, 2015). The four most important and relevant basic test procedures are cold water extract, hot water extract, organic solvent extract, and migration testing using modi fi ed polyphenylene oxide (MPPO, poly 2,6- diphenyl-p-phenylene oxide, e.g., Tenax ® ) as a simulant. All procedures are published as European Standards. The extracts are carried out under de fi ned conditions (sample weight, water/solvent volume, and contact time/temperature; Table 1). German BfR recommended slight modi fi cations to increase the intra- and inter-laboratory reproducibility of the water extracts. Cold and hot water extracts are considered to simulate direct aqueous food contact; the cold water extract represents aqueous foods and beverages at all applications except hot and baking applications. For these two applications, the hot water extract is used for water-soluble and hydrophilic substances. The organic solvent extract simulates contact with fatty foods by using 95% ethanol and isooctane as solvents. These extractions are carried out with cut samples. On the contrary, the MPPO test is a migration test, in which the adsorbent MPPO is spread on the food contact surface. MPPO simulates contact with dry foods and at high temperatures with all foods (microwave and baking applications). The test conditions are usually taken from Annex V of the Plastics Regulation (EU) 10/ 2011 (EU, 2011). The EURL-FCM guideline for testing conditions of kitchenware states examples for a variety of applications (Beldi et al., 2023). For high-temperature applications (microwave and oven), the recommended temperatures vary. EN 14338 gives a maximum temperature of 175 ° C for the test but does not give advice on the selection of test conditions. CoE Technical Guide proposes 2 h at 175 ° C for oven applications and 30 min at 150 ° Cfor microwave (CoE, 2021). EURL-FCM guideline — prepared by the EU reference and national surveillance laboratories — recommends conditions up to 2 h at 200 ° C, depending on the application in the oven and 30 min at 121 ° C for warming up or defrosting or at 175 ° C for cooking in the microwave (Beldi et al., 2023). According to German BfR at contact of 2 h at 220 ° C no degradation for baking papers should occur, and 30 min at 150 ° C for microwave applications should be applied (BfR, 2015). EURL-FCM guideline distinguishes between coated or treated paper articles, which do not absorb moisture or oil and withstand migration tests based on the conditions from Regulation 10/2011, and other paper articles. For the former, the conditions for plastic materials are given in table 5A of the guideline, and for the latter, the extraction and MPPO tests as described above (table 5B, there). Plastic migration processes have completely different characteristics compared with paper. Consequently, the contact conditions are not necessarily applicable to paper as discussed in depth below in Section 5. In addition to these tests, Council of Europe Technical Guide (CoE, 2021) recommends using 3% acetic acid for estimating the release of metals into acidic foods. Generally, for the contact test conditions, the guide refers to EURL- FCM guideline. The results of cold and hot water extracts in mg/L are considered conventionally equivalent to migration in mg/kg food (CoE, 2021). CoE Technical Guide states that the real ratio of surface area to the amount of food must be used or the maximum allowable surface-to- food ratio should be declared. By contrast, the EURL-FCM guideline
No. 1935/2004 (EU, 2004) and the Good Manufacturing Regulation (EC) No. 2023/2006 (EU, 2006). In short, these regulations lay down general principles to ensure that any food contact material is safe for the consumer and manufactured under quality-controlled conditions. Paper materials are listed in Annex 1 of 1935/2004 as materials, which may be covered by speci fi c EU measures but are not harmonized. Therefore, Article 7 of that Regulation foresees that national provisions can be maintained or adopted by Member States in the absence of EU-speci fi c measures. A total of 10 Member States (Belgium, Czech Republic, Estonia, Greece, Germany, France, Croatia, Italy, the Netherlands, and Slovakia) have set out their provisions and safety criteria in national regulations or recommendations. The latter, such as set out by the German BfR, are legally not binding but have almost the strength of legislation by the force of the market. A summary — including the limits for speci fi c substances — is given in Annex 16 of Simoneau et al. (2016). There is a high variety of rules, requirements, and substance lists with only little congruence between the Member States (Simoneau et al., 2016). The Council of Europe has recently released the general resolution CM/Res (2020)9 on the safety and quality of materials and articles in contact with food (CoE, 2020), which is applicable to non-harmonized materials in EU, giving detailed but not legally binding requirements regarding consumer safety. A speci fi c technical guide on paper and board (CoE, 2021) supplements this general resolution. Annex II gives some restrictions to speci fi c substances occurring within paper. Comprehensive and detailed overviews of the paper EU regulatory situation along with extensive lists of national provisions and measures can be found in the baseline study (Simoneau et al., 2016) and in review articles by Kourkopoulos et al. (2022) and Oldring et al. (2023). A matter of concern in the last decade was the presence of mineral oil components, especially aromatic hydrocarbons (MOAH) in papers with recycled fi bers, or from printing inks on food contact materials. The German Federal Ministry of Food, Agriculture and Consumer Protection (BMEL) proposed speci fi c migration limits for MOAH to be undetectable in food and food simulants at detection limits of 0.5 and 0.15 mg/kg food simulant. The respective national decree was not set into force pending a future European measure (BMEL, 2022b;a). Limits for mineral oil components in food are still discussed in EU (EC, 2023).
4 Normative framework of standard test methods and guidelines
Supporting and enforcing the European and national legislation for paper, more than 20 standard test methods and procedures are available on European and national levels (Simoneau et al., 2016; CoE, 2021; Oldring et al., 2023). These standards cover a range of test principles (determination of residual content, extraction, and migration), speci fi c target substances or substance groups (such as bisphenol A, anthraquinone, and phthalates), and other paper material parameters, including organoleptic testing, fastness of colors, or optical brighteners. Testing the transfer of substances from paper includes the step of transfer (migration, gas phase transfer, or extraction) and a speci fi c analytical method for the target substances (BfR, 2015). For
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