A human-centered review of life cycle assessments of bioplastics

Purpose Bioplastics are an often-touted alternative to reduce the environmental impacts of plastic usage, and potentially reduce reliance on petroleum sources, when compared to conventional plastics. Life cycle assessment (LCA) is a tool used to quantify the comparable environmental impacts throughout a product's life cycle. Although existing literature has focused on the raw materials and includes stylized use and disposal scenarios, gaps exist related to the role of human behavior and its subsequent environmental impact due to the real-world usage and disposal of bioplastic products. This is in part due to challenges in fully understanding the role of human behavior and incorporating it into LCA to generate meaningful results. This work seeks to identify these gaps through a review of current literature. The work contained herein is written from a United States (US) perspective with its solid waste infrastructure in mind and challenges specific to the US. Materials and methods A review of existing literature on human behavior in disposal of conventional plastics and bioplastics, and the degree of incorporation of in LCA studies, is conducted. This allowed for the identification of current gaps within the literature, such as the role of human behavior and decision-making, within the end-of-life scenarios. Results and discussion There is a significant body of literature that analyzes the cradle-to-gate impact of bio-based bioplastics from an LCA perspective. However, user behavior and end of life are studied less due to the challenges of predicting human behavior at disposal, modeling the boundaries, and issues of location specificity. There is conflicting evidence as to the benefits and adverse impacts of bioplastics when compared with conventional plastics, which may be further clarified through the incorporation of human behavior in the end of life of the bioplastic and conventional plastic products. Conclusions Bioplastics have been suggested as an opportunity to reduce the environmental impacts of plastic usage throughout their life cycle. Portions of the bioplastic life cycle have been well quantified in literature, such as raw materials and manufacturing, while the end of life has largely been incorporated as stylized scenarios. Bioplastic LCA literature does not fully capture the effects of true disposal in its findings. In order to capture these effects, a focus on the junction between end-of-consumer-use and entry into waste collection system is needed. To generate more comprehensive and holistic assessments, more research is required as to the role of human behavior and its consequential environmental impacts. This will lead to more realistic modeling and society level forecasts as to the comparative environmental impacts of bioplastic usage.