In an article in Frontiers in Sustainability, Sangwon Suh of the University of California Santa Barbara and co-authors propose a multi-criteria framework for identifying polymers of concern. Rather than focusing solely on the intrinsic properties of polymers, the authors argue that the impacts associated with their production, use, and entire life cycle should also be considered. The proposed criteria are intended, among other things, to help set science-based targets in the ongoing negotiations of the United Nations treaty on plastic pollution.
The triple planetary crisis is a term that refers to the overlapping issues of pollution, climate change, and biodiversity loss that international action is needed to mitigate. Plastics and polymers can contribute to these crises. They physically pollute the environment (FPF reported), thereby harming ecosystems and wildlife, they often contain hazardous substances (FPF reported also here) which can contribute to chemical pollution, and contribute to climate change since they are highly dependent on fossil-based resources for their production (FPF reported).
According to the authors, this plethora of impacts cannot be captured solely by the intrinsic properties of the main polymers, such as hazard, biodegradability, and bioaccumulation characteristics. Furthermore, these properties have not yet been fully characterized for many polymers (FPF reported). The authors thus developed a set of broader application- and life-cycle-based criteria. Specifically, they propose criteria for polymers of concern that focus on health and safety (including the impact of additives and other associated chemicals), environmental impacts throughout the life cycle, circularity potential, and environmental leakage. Previously proposed frameworks also suggest a more holistic assessment of polymers and plastics, rather than looking only at intrinsic properties (FPF reported).
Suh et al. provide a preliminary ranking of polymers based on their criteria. However, they note that more research and better data are needed to fully assess and compare polymers and their applications.
Similar to other investigations into the chemical safety of polymers, the health and safety concerns regarding chemicals were found to be particularly prominent for PVC, PP, and PS (FPF reported). Other polymers and plastics are also known to contain harmful chemicals or impact human health (see FCCmigex database, FPF reported), though seem to be relatively less concerning in comparison.
Packaging plastics, including those used for food packaging, are particularly likely to end up in the environment due to their high use volumes and short lifetimes (FPF reported). According to Suh, the application in packaging is a better predictor for environmental release than the polymer type. However, PP, PE, and PET (from textile fibers) are particularly associated with microplastic pollution (FPF reported).
Life-cycle emissions, including CO2 emissions, of polymers and plastics are highly variable and highly dependent on the production technology, feedstock, and energy sources used. Additionally, specific uses may require different amounts of polymers, thus simply comparing emissions on a per-kg basis is not sufficient.
The authors identify several important knowledge gaps, such as the chemical composition of different plastics, the effects of associated chemicals, models for the transport of plastics in the environment, and methods for quantifying their effects on ecosystem health. The author suggests that nonetheless, consideration of these different aspects is critical to determining the regulatory needs for polymers. The authors also suggest that, in line with the precautionary principle, urgent action should be taken for polymers of concern, despite some remaining data gaps.
References
Suh, S. et al. (2024) ‘Conceptual framework for identifying polymers of concern’. Frontiers in Sustainability. DOI: 10.3389/FRSUS.2024.1399431
Read more
Scientists’ Coalition for an Effective Plastics Treaty (2023). “Policy Brief: Role of chemicals and polymers of concern in the global plastics treaty”. DOI: 10.5281/zenodo.794152
