Chain Of Custody: Tracing Sustainability In The European Plastic Sector With A Closer Look At The Mass Balance Approach

Abstract

Transparency and traceability of materials within supply chains are becoming increasingly important, as reflected in recent EU policies and growing consumer demand. In addition, companies adopting sustainable practices—such as procuring recycled plastics—require robust methods to substantiate and verify their sustainability efforts. This paper explores methods of traceability and transparency in the European plastics sector, focusing in greater depth on the mass balance approach, which is especially relevant in the EU chemical recycling sector. Despite the crucial role that the mass balance method plays in chemical recycling—particularly in enabling recyclers to demonstrate the processing of sustainable feedstock —the allocation rules and accounting methods remain complex and unharmonized. Robust and transparent standards are essential for mass balance to enable wider application and to establish trust and greater credibility among stakeholders. However, where physical segregation of materials can be achieved, chain-of-custody methods with higher inherent credibility should be prioritized and applied instead.