Recycling is often seen as a key part of the solution to reducing plastic pollution. However, increasing scientific evidence shows that plastics recycling implies chemical safety challenges (FPF reported and here). Two recent scientific articles published in the Journal of Hazardous Materials in February 2025, provide further evidence and demonstrate that whole migrate toxicity testing, i.e. assessing all chemicals that transfer out of (recycled) plastics, is key to ensuring (recycled) plastics are safe for use in food contact. Another, third article develops a strategy for safer plastics and makes recommendations for policy makers.
Chemical hazards increase with recycling
Lakshmi Daggubati and co-authors from the University of Newcastle, New South Wales, Australia found that recycled plastics contain higher concentrations of chemicals than virgin plastics, e.g., double the levels of per- and polyfluoroalkyl substances (PFAS). In their article published February 4, 2025, they report that polyaromatic hydrocarbon (PAH) levels were three times higher and metal(loids) levels even ten times higher in recycled compared to virgin plastics. The recycled plastic also contained more non-intentionally added substances (NIAS), such as contaminants introduced during a product’s life cycle or chemical reaction by-products generated during its recycling. “Identifying and controlling NIAS in recycled materials is challenging,” the authors highlighted.
In addition, Daggubati and co-authors assessed the physical characteristics of the products. Recycled plastics had a higher surface area due to changes in the surface morphology, making them more prone to both releasing and adsorbing chemicals, as well as to generating microplastics. Based on previously reported daily microplastic intake levels and assuming that all detected PFAS, PAHs, and metal(loids) are fully available, the researchers calculated the non-cancer Hazard Index from microplastic ingestion. The Hazard Index increased twofold for recycled plastics compared to virgin plastics. Even though only a limited set of chemicals was considered in the calculations, the Hazard Index for recycled plastic ingestion was higher than one, placing them in “the high-risk category.”
In their study, the scientists included virgin and recycled plastic products from global suppliers intended for food, oral, or skin contact applications made of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). They investigated the products by Attenuated Total Reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and their extracts by non-targeted and targeted analysis (for 13 metal(oids), 16 PAHs, and 24 PFAS).
Appropriate decontamination essential for recycling
In their article published on February 8, 2025, Rachelle D. Arcega from National Cheng Kung University, Tainan, Taiwan, and co-authors reported that the toxicity of chemicals migrating from plastic recycled in Taiwan decreased with the recycling steps, indicating the importance of decontamination during the recycling process. Generally, chemicals released from recycled PET were found to be of higher toxicity than those from recycled PP and PE. The authors further pointed out that their virgin PET samples were even more cytotoxic than recycled PET samples. Importantly, the virgin PET assessed was not the precursor of their recycled PET assessed and might have had a completely different chemical composition, making a comparison not meaningful.
The scientists took samples of PET, PP, and PE intended for food contact at different stages of the plastic recycling process and performed migration experiments with food simulants (water, 4% acetic acid, 20% ethanol, and n-heptane). Chemical analysis was performed on the migrates using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and gas chromatography mass spectrometry (GC-MS). Migrates were further applied to in vitro assays to test for general cell toxicity, i.e. cytotoxicity (3T3 NR uptake assay) and for specific target organ toxicity to kidney and liver, i.e. nephrotoxicity/hepatotoxicity (high-content screening).
Moving towards safer (recycled) plastics
Bethanie Carney Almroth from the University of Gothenburg, Sweden, and co-authors published an article on January 16, 2025, in the journal Cambridge Prisms: Plastics, providing policy makers with five steps for addressing hazardous chemicals in recycled plastics and transitioning towards safer and more sustainable plastics. Unlike Arcega et al., Almroth and co-authors pledge to address chemicals not only during the recycling process (by decontamination) but also in virgin plastics. The five policy strategies are
- “improved reporting, transparency, and traceability of chemicals in plastics throughout their full life cycle;
- chemical simplification and group-based approaches to regulating hazardous chemicals;
- chemical monitoring, testing, and quality control;
- economic incentives that follow the waste hierarchy; and
- support for a just transition to protect people, including waste pickers, impacted throughout the plastics life cycle.”
The researchers further clarified that several plastics value actors need to adopt these best practices and highlighted the importance of the global plastics treaty to include obligations on the policy level to make this transition to safer and more sustainable recycling happen.
To learn more about the recycling of plastic and other food packaging materials, have a look at the Food Packaging Forum’s (FPF’s) fact sheets. FPF has also published a concept for testing the overall migrate of food contact materials, using New Approach Methods (NAMs; FPF reported).
References
Arcega, R. D., et al. (2025). “Toxicity evaluation and prioritization of recycled plastic food contact materials using in silico tools.” Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2025.137467
Carney Almroth, B., et al. (2025). “Addressing the toxic chemicals problem in plastics recycling.” Cambridge Prisms: Plastics. DOI: 10.1017/plc.2025.1
Daggubati, L., (2025). “Fingerprinting risk from recycled plastic products using physical and chemical properties.” Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2025.137507
