Review of plastic footprint methodologies: Laying the foundation for the development of a standardised plastic footprint measurement tool.

Abstract

Of the 8,300 million tonnes (Mt) of plastic produced from 1950 to 2015, only 7% has been recycled while more than half has been discarded in landfill or leaked into the environment. Plastic leakage into the environment demonstrates a systemic failure of the take-make-dispose consumption model and makes clear the need for a shift towards more circular material flows. With 10 Mt of plastics leaking into the ocean annually (Boucher & Friot, 2017) from a variety of sources, improving the circularity of plastic flows, from source-to-sea is key. Companies, organisations, and governments are taking measures to tackle plastic pollution. However, as recognised during the Third United Nations Environment Assembly (UNEA- 3, Nairobi, 2017), there is currently no standard methodology to measure the extent of the plastic problem. Countries and other stakeholders were encouraged to “cooperate to establish common definitions and harmonized standards and methodologies for the measurement and monitoring of marine litter and microplastics”. Only if equipped with credible, salient and legitimate data and analyses can decision-makers understand their current status, set targets, agree and implement actions, and track progress towards targets over time.. Recognising the needs identified in the UNEA-3 resolution, this report provides a review of existing and emerging methodologies to identify the abundance, distribution, types, sources, pathways and sinks of plastic pollution at different scales. It also provides an overview of the state of knowledge for impact assessment and monetary valuation methodologies, along with a glossary of key terms related to plastics, marine plastics and environmental footprints. The review of methodologies covers 19 that had been identified as of early 2019. An analysis reveals two groups of methodologies: the first comprises those that identify plastic waste streams and recycling rates at the national or business level; the second comprises methodologies that focus on pathway modelling to measure plastic leakage into waterways and oceans, from either mismanaged waste or in the form of microplastics. An analysis of the review concludes that there could be stronger convergence between methodologies in this fast-developing area and that plastic footprint methodologies are lacking in several ways