The widespread, intentional use of per- and polyfluoroalkyl substances (PFAS) in food contact materials (FCMs) are known to be a direct exposure route for humans via chemical migration (FPF reported). The intentional use and release of such highly persistent chemicals goes against principles of responsible chemistry and looks to be leading the Earth towards a chemical pollution tipping point beyond current planetary boundaries (FPF reported also here).
Five research, review, and viewpoint articles published between October and December 2023 investigated PFAS presence and migration from FCMs, impacts on the human liver, and a group of PFAS substitutes.
Presence and migration from plastic bags
In an article published on November 22, 2023, in the Journal of Chromatography Open, Kevin M. Stroski from USDA, Agricultural Research Service, Wyndmoor, USA, and Yelena Sapozhnikova from Baylor University, Waco, USA, analyzed 18 plastic food storage bags acquired in Philadelphia, USA for PFAS presence and levels. Upon performing extraction and migration experiments, the scientists did a targeted analysis for 35 PFAS as well as a non-targeted analysis using liquid chromatography-tandem mass spectrometry and Orbitrap high-resolution mass spectrometry.
By targeted analysis, the authors detected PFAS in 57% of the extraction samples in concentrations between 0.5 and 26.6 ng/g packaging. Of the 35 PFAS, they only found two, perfluorobutane sulfonate (PFBS, CAS 375-73-5) and 6:2 fluorotelomer phosphate diester (6:2 diPAP, CAS 57677-95-9), with the latter being present most frequently. In the non-targeted screening, six additional PFAS candidates were detected but due to the lack of analytical standards, their identity could not be confirmed.
Performing migration experiments on eight bags, only PFBS was present in the samples and levels were between 5.9 and 20 ng/g packaging. The steady-state concentration was already reached after 2 hours of migration, meaning concentrations in the samples stayed the same as the experiment continued indicating “that even brief contact with the tested plastic storage bag can result in rapid migration of PFBS.” Based on the migration data, the scientists further calculated the potential weekly intake of PFBS to be 2.12 ng/kg body weight. Since no regulatory threshold value existed for PFBS, they compared it to the European Food Safety Authority’s (EFSA’s) tolerable weekly intake value for the sum of four specific PFAS which is 4.4 ng/kg. The detected PFBS values were well below it.
PFAS in single-use food packaging
On December 13, 2023, IPEN, a non-profit umbrella organization comprising 600 public interest NGOs, published a report on PFAS use and contamination in single-use paper, cardboard, and plant-based food packaging and tableware. Jitka Straková and co-authors assessed samples from 17 countries across Asia, Africa, Europe, Latin America, and the Caribbean including fast-food wrappers, takeaway cardboard boxes, coffee cups, microwave popcorn bags, and many more.
Samples were extracted with a mixture of methanol and ethyl acetate, and extractable organic fluorine (EOF) was then analyzed by combustion ion chromatography (CIC) to determine the total PFAS amount. According to the authors, 64 of the 119 samples contained PFAS. Among them was fast-food packaging from major brands. Plant-based molded fiber products, labeled as biodegradable or compostable, contained the highest PFAS concentrations, while microwave popcorn bags contained them most frequently.
Comparing PFAS quantities to regulatory limits, the authors found that four “samples contained PFAS above EU limits for PFOA (25 ppb) and/or for long-chain PFCAs (25ppb for the sum of C9-C14 PFCAs).” Another “53 samples contained Extractable Organic Fluorine or individual PFAS above the proposed limits in the EU REACH universal restriction.” Of the 58 targeted PFAS, 21 were detected in the samples and quantified. Interestingly, 98% of the PFAS content could not be identified, meaning only 2% of the chemical identities could be determined by targeted analysis.
The report concluded that “setting legislative thresholds for a few small groups of PFAS is not sufficient to control these harmful substances in food packaging. Only a universal ban, including polymeric PFAS, can stop human exposure and release from food packaging.” It recommends banning PFAS and their substitutes by the Stockholm Convention and governments.
PFAS exposure and liver disease
In an article published on October 21, 2023, in the journal Science of the Total Environment, Jinfeng Zhang and co-authors from Nanchang University, China, reviewed the literature published on Web of Science within the last five years on PFAS exposure and the link to human liver disease.
Considering epidemiological studies, outcomes of in vitro models, and in vivo rodent studies, the authors reported that PFAS have been linked to hepatic cytotoxicity, oxidative stress, glycolipid metabolism disorder, and bile acid metabolism dysregulation. However, epidemiological evidence only exists for a small subset of PFAS, e.g., perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononan-1-oic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS) which have been positively correlated with liver damage and disease. On the other hand, the health effects of emerging, less well-studied PFAS and PFAS mixtures remain largely unknown. Furthermore, Zhang and co-authors pointed out that the dose administered in in vitro and in vivo studies often exceeds the PFAS levels in the environment. They call for investigations under relevant human exposure levels. In addition to impacts on the human liver, the review summarizes the sources of PFAS, their occurrence in food systems, the characteristics of dietary exposures, and critical knowledge gaps.
Investigating PFAS substitutes
Junjie Ao and co-authors from Shanghai Jiao Tong University School of Medicine, China, summarized the occurrence, toxicokinetic, and negative impacts of PFAS substitutes, the so called polyfluoroalkyl phosphate esters (PAPs). Their review article, published on November 17, 2023, in the Journal of Hazardous Materials, raises awareness for the safety issues connected with these PFAS substitutes.
PAPs are a family of phosphoric acid esters consisting of one, two, or three polyfluoroalkyl groups (monoPAPs, diPAPs, and triPAPs, respectively) with applications in FCMs as grease and water repellents. Due to their C-F bond, they have strong stability in the abiotic environment. Ao and co-authors summarized that 6:2 diPAP is the most prevalent PAP in all analyzed matrix samples from food to human blood to wastewaters. Upon entering the human body, biotransformation leads to the generation of multiple perfluorinated carboxylates (PFCAs), the authors continued. “PFCAs can resist catabolism and phase II conjugation, and are poorly excreted in the body.” Existing epidemiological and toxicological studies indicate that PAPs may cause endocrine disruption (e.g., estrogenic, antiandrogenic effects, and thyroid disruption) as well as reproductive toxicity.
Microplastics and PFAS
In a viewpoint article published on December 8, 2023, in the journal ACS ES&T Water, Sarawut Sangkham from the University of Phayao, Thailand, pointed out that microplastics may influence the effects of PFAS in the environment. Sangkham descibes that plastic litter represents a combined source of microplastics and PFAS (besides many other chemicals) and highlights that the interaction of MPs and PFAS in the environment is poorly understood. Currently available studies would, for instance, indicate that microplastics act as a carrier for PFAS, mediating their accumulation in animals. Furthermore, “biodegradation of microplastics can either enhance or diminish the release of PFAS pollutants into the environment.” He called for more research on the combined effect of microplastics and PFAS since their coexistence in the environment could be “a significant threat to ecosystems.”
Several US state policies address PFAS (FPF reported) and in November 2023, the European Parliament adopted an amended Packaging and Packaging Waste Regulation (PPWR), including a ban on PFAS in food packaging (FPF reported).
References
Ao, J. et al. (2023). “Polyfluoroalkyl phosphate esters (PAPs) as PFAS substitutes and precursors: An overview.” Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2023.133018
Straková, J., et al. (2023). “Forever Chemicals in Single-use Food Packaging and Tableware from 17 Countries.” IPEN. DOI: 10.13140/RG.2.2.34952.39687 (pdf)
Stroski, K. M., and Sapozhnikova, Y. (2023). “Analysis of per- and polyfluoroalkyl substances in plastic food storage bags by different analytical approaches.” Journal of Chromatography Open. DOI: 10.1016/j.jcoa.2023.100106
Sangkham, S. (2023). “Global Perspective on the Impact of Plastic Waste as a Source of Microplastics and Per- and Polyfluoroalkyl Substances in the Environment.” Science of the Total Environment. DOI: 10.1021/acsestwater.3c00607
Zhang, J. et al. (2023). “Dietary exposure to per- and polyfluoroalkyl substances: Potential health impacts on human liver.” ACS ES&T Water. DOI: 10.1016/j.scitotenv.2023.167945
