In March 2022, 175 nations agreed to develop a legally binding treaty to end plastic pollution which shall be created by 2024 (FPF reported). Negotiations are already underway (FPF reported) but ongoing research continues to shape the discussion. How many corporations have made voluntary plastic pollution-related commitments and of what kind? What role does recycling play? And what about the chemicals that are present in recycled materials, particularly in polyethylene terephthalate (PET)? Five articles published at the end of 2022 took on this topic.
In an article published on November 18, 2022, in the journal One Earth, Zoie Diana from Duke University, Beaufort, NC, USA, and co-authors evaluated the voluntary commitments to reduce plastic pollution made by the world’s largest companies. The authors evaluated 973 companies including the top 300 companies on the Fortune Global 500, those with more than $10 billion revenue annually and participating in global voluntary environmental programs (i.e., Ellen MacArthur Foundation’s Global Commitment, UN Ocean Conference, Our Ocean Conference), and companies assumed to have the greatest impact on plastic pollution reduction. In addition to analyzing the companies’ corporate reports published between 2015 and October 2020, Zoie and co-authors discussed the effectiveness of voluntary commitments by reviewing scientific studies, news articles, and industry reports.
The scientists reported that 72% of the top 300 companies on the Fortune Global 500 have commitments to reduce plastic pollution according to publicly available reports. Over the analyzed period, the mentioning of keywords connected with plastic pollution (i.e., plastic recycling, plastic waste, circular economy) increased suggesting “an increased awareness of the issue.” Summarizing the results of five peer-reviewed papers, the authors ascribe the motivation to external pressures (e.g., due to third-party certification), consumer demand, and economic and reputational advantages. Measurable and timebound commitments were more likely to be made by companies participating in voluntary environmental programs (67%) compared to those not participating (17%).
However, the authors further pointed out that commitments most commonly refer to plastic recycling. This would “exclude and divert investment in preventive measures that may reduce virgin plastic production and promote reusable and alternative delivery systems.” Interestingly, according to industry association reports published earlier in 2022, in Europe, plastic recycling has not increased substantially over the last years and two-thirds of plastic-packaging pledges from food and drink companies failed (FPF reported).
Overall, Zoie et al. think that their presented frameworks can help to monitor large companies’ voluntary corporate commitments systematically thereby “advancing corporate accountability and accounting for these commitments in global models of plastic use, waste, and leakage into the environment.”
While Zoe et al. looked at plastics in general the Food Packaging Forum’s (FPF’s) Brand & Retailer Initiatives Database (BRID) summarizes voluntary initiatives and commitments by food brands and retailers to improve the chemical safety and resource efficiency concerning all food contact materials and food processing equipment.
One major problem connected with recycling plastic waste into new products is that chemicals may be carried from the previous into the new product (FPF reported, also here and here). In a review article published on November 22, 2022, in the journal Science of the Total Environment, Ed Cook from the University of Leeds, United Kingdom, and co-authors focused on theses “inherited” (i.e., legacy) substances as well as on the extrusion process of recycled plastics. Thereby, the authors aimed to give an overview of human health risks associated with the reprocessing of plastic waste.
Cook and co-authors searched Scopus, Web of Science, and Google Scholar with terms tailored to plastic waste and processing type, as well as harm to humans or the environment. They screened the literature for eligibility and coded it according to uncertainty, the strength of knowledge, and methodological robustness. They further coded risks and hazards by their type and pathway and ranked the relative risk caused by different activities.
Of the 4,409 identified publications, 20 were included in the review. Cook et al. grouped potentially hazardous compounds into brominated flame retardants, phthalates, potentially toxic elements (e.g., lead, chromium), and other volatile organic chemicals. Legacy compounds from all of these groups are present in recycled plastic products available in high-income countries. This would indicate that “the recycling part of our circular economy does not necessarily provide for safe and final sinks for substances of concern in plastics.”
Although the substances’ concentrations were mostly below regulatory safety limits, the authors highlighted that their presence even in plastics of regions with the most stringent controls suggests “a wider or possible increase in pollution dispersion.” Concerning extrusion, Cook and co-authors summarized that this process, which involves heating the plastics, would favor the release of plastic chemicals. Workers in some parts of the Global South in particular would not be protected from occupational exposure to plastic chemicals.
Katie G. Steimel and co-authors from Stantec (ChemRisk), Aliso Viejo, CA, USA, reviewed the literature available on chemicals leaching from PET and recycled PET bottles. In their article published on December 13, 2022, in the journal Reviews on Environmental Health, the authors described that they searched the literature published before May 2022 and included the studies that analyzed both PET and recycled PET bottles by using the same method and gave the concentration of leached chemicals. Only three studies met their inclusion criteria.
Steimel and co-authors reported that the three papers together studied nine chemicals. With the increased percentage of recycled content, the quantity of bisphenol A (BPA, CAS 80-05-7), benzene (CAS 71-43-2), and styrene (CAS 100-42-5) increased, while that of furan (CAS 110-00-9) and 2-methyl-1,3-dioxolane (CAS 497-26-7) decreased. For the others, acetone (CAS 67-64-1), 2-butanone (CAS78-93-3), and limonene (CAS 5989-54-8), no trend was observed. For instance, with an increase in recycled content from 0 to 100%, styrene increased from <0.01 to 0.063 µg/L and bisphenol A from <0.1 to 4.2 ng/g whereas furan decreased from 0.08 to 0.05 µg/L. The authors concluded that “recycling PET can lead to changes in the leachable profile.” They further clarified that studies need to be performed that use different liquids, bottle reuse scenarios, and UV-light exposures, as well as consider other chemicals of concern (e.g., antimony).
An experimental study published on November 15, 2022, by Ben Dong from the Guangzhou Customs Technology Center, China in the peer-reviewed Journal of Hazardous Materials, analyzed volatile contaminants in 57 batches of recycled PET flakes available in China.
By comparing three previously published gas chromatography-based techniques, the researchers developed a method allowing them to screen volatile chemicals in an untargeted manner. They found head-space solid phase micro-extraction combined with comprehensive two-dimensional gas chromatograph-tandem quadrupole-time-of-flight mass spectrometry (HS-SPME-GC×GC–QTOF-MS) to be “a sensitive, effective, accurate method” for their purpose. Using this technique, the scientists screened the 57 PET flake samples from three different geographical recycling regions to tentatively identify their volatile chemicals. The identified chemicals were then compared against different databases and lists to determine their origin (e.g., FPF’s Database of Chemicals associated with Plastic Packaging (CPPdb)) and toxicities (i.e., the EU’s carcinogenic, mutagenic, and reprotoxic chemicals (CMR) list, the European Chemical Agency’s Candidate List of substances of very high concern (SVHC), and the International Panel on Chemical Pollution’s overview report on endocrine disrupting chemicals (EDCs)). Based on these toxicities and the Threshold of Toxicological Concern (TTC), toxicities were classified into different levels.
Dong and co-authors tentatively identified 212 volatile chemicals in the samples. According to their toxicity rating, 45 were high-priority substances due to public health concerns. Regarding the substances’ origins, the authors connected them with plastics, food, and cosmetics. Considering the chemical varieties and quantities, Dong et al. found that the flakes differed greatly between the three geographical regions. The scientists highlighted the need to collect comprehensive data on the contamination of recycled PET intended for applications in food contact throughout China.
One type of non-intentionally added substances (NIAS) present in PET and their recyclate, is PET oligomers. Due to the limited availability of reference standards for PET oligomers, the technical challenge of detecting the often low concentrations, as well as the fact that they are not currently regulated by the European packaging regulation, the presence and migration of PET oligomers has rarely been studied.
In an article published on December 25, 2022, in the journal Molecules, Verena Schreier from the University of Basel, Switzerland, and co-authors developed and presented an approach on how to model the migration of PET oligomers under realistic use conditions. The authors think that “migration models represent a useful tool for the safety evaluation of PET” since it is fast, comprehensive, and can be performed even if migration testing data is missing. Schreiner and co-authors highlighted three major parameters which need to be considered when evaluating the exposure to oligomers from PET with migrations models: (i) “Small oligomers with high diffusion coefficients are the most critical substances that can also pose the greatest risk to consumers, especially when the storage conditions include high temperatures”, (ii) the partitioning coefficient can be neglected due to the slow diffusion of comparably high molecular weight PET oligomers in PET, and (iii) the concentration of oligomers in PET.
Together with scientists from FPF and others, Schreier is currently collecting all known exposure and hazard data of oligomers migrating from PET food contact materials (FPF reported).
References
Cook, E. et al. (2022). “Plastic waste reprocessing for circular economy: A systematic scoping review of risks to occupational and public health from legacy substances and extrusion.” Science of the Total Environment. DOI: 10.1016/j.scitotenv.2022.160385
Dong, B. et al. (2022). “Occurrence of volatile contaminants in recycled poly(ethylene terephthalate) by HS-SPME-GC×GC-QTOF-MS combined with chemometrics for authenticity assessment of geographical recycling regions.” Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2022.130407
Schreier, V. et al. (2022). “Migration Modeling as a Valuable Tool for Exposure Assessment and Risk Characterization of Polyethylene Terephthalate Oligomers.” Molecules. DOI: 10.3390/molecules28010173
Steimel, K. G. et al. (2022). “Evaluation of chemicals leached from PET and recycled PET containers into beverages.” Reviews on Environmental Health. DOI: 10.1515/reveh-2022-0183
Zoie, D. et al. (2022). “Voluntary commitments made by the world’s largest companies focus on recycling and packaging over other actions to address the plastics crisis.” One Earth. DOI: 10.1016/j.oneear.2022.10.008
