(217c) A Material Flow Analysis for Sustainable End-of-Life Plastic Management

Global plastic production was estimated to reach 360 million tons in 2018. The production phase begins with raw material, monomer synthesis, polymerization, followed by the compounding of chemical additives to create plastic for consumer use. However, over 90% of the spent plastics were either landfilled or incinerated, with both solutions being susceptible to releasing toxic substances and greenhouse gases into the environment. For instance, chemical additives may migrate out of the original plastic under certain conditions, contaminating its surroundings and harming the environment and human health. Continuous exposure to these chemicals over time will cause bioaccumulation of toxins, thus leading to unwanted consequences on human health. Despite these negative effects, chemical additives remain essential in plastic manufacturing for improving processability and properties during use. An improvement to the existing infrastructure for plastics end-of-life (EoL) management is needed to prevent and control chemical additive releases and potential risk and exposure. Therefore, this work aims to develop generic EoL processing scenarios to track and estimate the possible migration, emission, and release of plastic additives throughout the plastic EoL stage. A material flow analysis of the plastic life cycle was performed using available U.S. municipal solid waste data and published research to track plastics and chemical additives movement during the EoL stage management activities, including mechanical recycling, incineration, and landfilling. Our analysis identified the mass flow transfers, gas-phase emissions, chemical additive migration, and subsequent releases from post-consumer plastic materials. The potential releases, hazards, and risks identified in this work create an opportunity to design a safer closed-loop plastic recycling infrastructure to strategically handle chemical additives and support implementing sustainable materials management efforts to transform the U.S. plastic economy from linear to circular.