Towards safe plastic recycling: A novel framework for identifying chemicals of concern in plastic waste

Circular Economy (CE) principles seek to eliminate hazardous substances and promote the reuse and recycling of plastic products. However, implementing these principles is challenging due to the wide variety of substances used in plastics, their potential health and environmental risks, the complexities of global supply chains, and concerns regarding reappearance of Chemicals of concern (CoCs) in post-recycled plastics (PRP). This study presents a novel approach for identifying CoCs in the waste stream by assessing the potential presence of chemicals in polymers across different industrial sectors and their hazard categories. With the objective of identifying CoCs that are most problematic regarding their reappearance in new products, selected CoCs are classified into four priority groups based on their physicochemical properties and molecular structures, for further risk and regulatory assessment. The first group includes 88 CoCs, that must be avoided in a circular economy, of which 70% are metalloids and 30% are organic additives. The second group comprises 167 CoCs, mainly additives, whose risks depend heavily on their concentration and specific use in products. The third and fourth groups consist of CoCs that are less frequently found in plastic waste and thus associated with relatively lower risks. Overall, this study offers a practical and adaptable tool to support the identification of hazardous substances in plastic waste, helping stakeholders make informed decisions by removing CoCs and promoting the development of safer alternatives for substitutions.