What are sustainable plastics? A review of interrelated problems and solutions to help avoid unintended consequences

Abstract Plastics are affordable and versatile, but there is a growing awareness that they are unsustainable in a number of ways, including concerns about climate, health and biodiversity. A number of solutions are being explored that could enable a more sustainable plastics system. So far, most research has focused on isolated technical solutions that address only one specific sustainability challenge posed by plastics, such as end-of-life management or feedstock alternatives to fossil fuels. Some interventions might mitigate one problem but contribute to another at a different stage of the plastics life cycle. This study is based on a literature review and adopts qualitative system dynamics to analyse the unsustainability of plastics with a holistic, integrative approach. The review shows that there is still no agreed definition of sustainable plastics, so the authors propose one based on inputs from the literature. The paper provides an overview of the impacts of potential solutions on the plastics system, highlighting how some interventions could end up having unintended consequences, perhaps even overshadowing the benefits. The results highlight the need for improved communication transparency between plastics stakeholders and a more vertically integrated, harmonised value chain to effectively implement a sustainability transition in the plastics system.