Three articles evaluated chemicals that migrate or are extractable from new and recycled paper & board food contact materials (FCMs), focusing on per- and polyfluoroalkyl substances (PFAS), organophosphate esters (OPEs), and plasticizers.
In a review article published on December 1, 2022, in the journal Food Packaging and Shelf Life, Michaela Lerch from the Technical University of Denmark, Lyngby, Denmark, and co-authors provide an overview of migration of PFAS from paper FCMs into food, compare it with the migration in food simulant, and assess consumer risk by dietary exposure. PFAS are widely used in paper and cardboard to provide resistance to water, oil, and other fats and have been associated with several adverse health effects (FPF reported and here).
Lerch and co-authors evaluated the methodological approaches scientists apply to analyze PFAS migration from paper FCMs. They summarized that most studies looked at PFAS in real food or food simulants and quantified certain PFAS by liquid chromatography followed by tandem mass spectrometry (LC-MS/MS). While in Europe currently no regulations exist on how to perform migration experiments on paper FCMs the Council of Europe recommended deploying those developed for plastic FCMs. This approach is also the one chosen most commonly in scientific analysis. Lerch et al. pointed out that “knowledge regarding the migration behavior of PFAS from paper-based FCMs is scarce” especially concerning factors potentially influencing PFAS migration such as material properties (e.g., thickness), composition, and unintended or misuse of packaging. Moreover, they emphasized, “that the use of food simulants (especially Tenax®) in migration tests lead to an underestimation of PFAS exposure from FCMs.”
Besides summarizing the migration behavior of PFAS from paper FCMs and the factors that could impact it, the authors also calculated the risk of dietary exposure to PFAS. To this aim, they used food consumption data from the European Food Safety Authority (EFSA) Comprehensive European Food Consumption Database and PFAS migration data from studies that performed tests with real food samples. They compared the exposure with the tolerable weekly intake (TWI) value established by EFSA, 4.4 ng/kg body weight/week, for the sum of perfluorononanoic acid (PFNA, CAS 375-95-1), perfluorooctanoic acid (PFOA, CAS 335-67-1), perfluorooctane sulfonate (PFOS, CAS 1763‑23‑1), and perfluorohexanesulfonic acid (PFHxS, CAS 355-46-4). The scientists estimated a TWI of 0.37 to 1.50 ng/kg bw/week. However, PFHxS was not included, and neither were all the other PFAS that have reported migrating from paper FCMs. While Lerch and co-authors mentioned 19 compounds, the Food Packaging Forum’s (FPF’s) Database on Migrating and Extractable Food Contact Chemicals (FCCmigex) lists 55 PFAS which have been detected in extraction or migration experiments with paper & board FCMs.
Lerch et al. also calculated the total weekly intake of PFOA equivalents which was found to range from 28 to 125 ng/kg bw/week, exceeding EFSA’s TWI. This would indicate “the potential severity of PFAS migration from FCMs into foods.” In addition to further research on the migration behavior of PFAS from paper FCMs, the authors also advocate for “the improvement of general guidelines regarding migration tests for paper and cardboard FCMs.”
Elisa Sonego from Sapienza University of Rome, Italy, and co-authors experimentally analyzed the migration of PFAS and also organophosphate esters (OPEs) from baking paper as well as from aluminum foil. Their article was published on December 23, 2022, in the journal Food Chemistry. OPEs substitute brominated flame retardants and may also act as plasticizers. Researchers have demonstrated the extensive contamination of Chinese foodstuff with OPEs (FPF reported) and uncovered paper food packaging as a source of these OPEs (FPF reported). FPF’s October 2022 Fact Bite on OPEs illustrates the amount of OPEs that have been detected together with the FCM type.
Sonego and co-authors acquired 11 baking paper and 11 aluminum foils from supermarkets in Rome between November 2022 and July 2021. They subjected unused and heat treated (to mimic baking) FCMs to migration experiments using 95% ethanol and 3% acetic acid to mimic contact with fatty and aqueous-based foods, respectively. Since the scientists were interested in examining worst-case food contamination, they performed migration with an ultrasound-assisted technique. Subsequently, they used high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) to detect and quantify OPEs and PFAS in a targeted manner.
The researchers reported both OPEs and PFAS migrated from aluminum foil and baking paper but levels changed with the material and the food simulant. Concerning baking paper, migration quantities into 3% acetic acid (the aqueous food simulant) were between 78.30 and 413.21 ng/dm2 paper and up to 10 times higher than into 95% ethanol (the fatty food simulant). The most prominent OPEs were triethyl phosphate (TEP, CAS 78-40-0) detected in all samples in concentrations up to 327.37 ng/dm2 and tris(2-butoxyethyl) phosphate (TBEP, CAS 78-51-3.) detected in 10 samples in concentrations up to 83.21 ng/dm2. PFAS migration ranged from 1.43 to 13.87 ng/dm2 and perfluoro-n-butanoic acid (PFBA, CAS 375-22-4) was the PFAS most frequently detected (0.10 – 1.68 ng/dm2). Concerning aluminum foil, migration quantities were comparable between the two types of food simulants. For instance, OPE migration in 3% acetic acid ranged from 13.19 to 61.52 ng/dm2. Generally, PFAS migrated in lower levels from aluminum foil than did OPEs. The most prevalent PFAS was PFOA in concentrations between 0.01 and 0.26 ng/dm2.
Sonego and co-authors summarized that “simulant contamination was mainly due to OPEs release” and, therefore, future studies should further elucidate the migration of OPEs from FCMs. But they also highlighted that “banned PFAS at not-negligible concentrations” could migrate showing “that the ban of the use is not enough to assure consumer protection.”
According to a review published in 2021, PFAS are still widely used in baking paper (FPF reported). In the US, states are developing local PFAS regulations with some states banning intentionally added PFAS in paper packaging (FPF reported and here) and five European nations are drafting a dossier to restrict PFAS in the EU entirely (FPF reported).
The European Paper Recycling Council reported that “in 2020, 73.9% of all paper and board consumed in Europe was recycled” (FPF reported). It is not common practice to separate the collected paper into food-grade and non-food-grade items before recycling (see FPF factsheet). Consequently, chemicals not intended for food contact, including such hazardous to human health, have been detected in recycled paper and board food packaging (FPF reported). In an article published on December 15, 2022, in the journal Sustainable Chemistry and Pharmacy, Ioanna-Efpraxia Parigoridi and co-authors from the University of Ioannina, Greece, identified and quantified seven plasticizers in recycled paperboard intended for being applied in contact with food. Specifically, they intended to develop a sensitive, effective, and accurate extraction method for this purpose. Therefore, the scientists optimized and compared three methods, soxtec extraction, ultrasound-assisted extraction, and head space-solid phase micro extraction (HS-SPME).
The researchers acquired three paperboard samples intended for packaging dry foodstuff consisting of 100% recycled pulp matter from a Greek production company. They applied the three extraction methods to the samples and analyzed the extracts with gas chromatography–mass spectrometry (GC-MS) for the presence of the seven plasticizers. In addition, they performed migration experiments with Tenax® (simulating dry foods) heating the samples to 70 °C for 2 hours.
Parigoridi and co-authors reported that all three methods have the potential to effectively determine the seven plasticizers in paperboard. However, “the HS-SMPE analysis, in conjunction with the GC/MS method, is not only simple and rapid but also quite sensitive and is, therefore, the most suitable for routine analysis of common plasticizers found in recycled paperboard.” The authors recommended integrating this method in the pulp manufacturing process to analyze plasticizers and make sure that the recycled product is safe and suitable for food contact applications. Looking at the compounds’ migration, it was found that di-n-butyl-phthalate (DBP, CAS 84-74-2) and di-2-ethyl hexyl phthalate (DEHP, CAS 117-81-7) migrated from the recycled paperboard samples into Tenax® above the proposed specific migration limit (SML). DEP migrated from all samples “well above the proposed SML values of 300 µg/kg.”
References
Parigorid, I.-E. et al. (2022). “Development of a reliable extraction method for the identification and quantification of 7 plasticizers in recycled paperboard materials intended for food contact applications.” Sustainable Chemistry and Pharmacy. DOI: 10.1016/j.scp.2022.100941
Lerch, M. et al. (2022). “Food simulants and real food – What do we know about the migration of PFAS from paper based food contact materials?” Food Packaging and Shelf Life. DOI: 10.1016/j.fpsl.2022.100992
Sonego, E. et al. (2022). “Occurrence and migration study of chemicals from baking paper and aluminium foil.” Food Chemistry. DOI: 10.1016/j.foodchem.2022.135260
