Life cycle assessment in recycling systems: trends, challenges, and gaps

Life Cycle Assessment (LCA) represents a robust framework for evaluating the environmental performance of recycling systems; however, its application to closed-loop strategies remains methodologically challenging, and standardized guidelines are still scarce. This article presents a systematic review of 196 recent papers (2020–2025) to analyze current methodological trends, identify key analytical choices across all industrial sectors, and provide recommendations for future assessments. The findings highlight a growing research interest, concentrated primarily in EU countries. However, substantial discrepancies emerge in how studies address technical modeling choices. Notably, there is a strong dominance of attributional over consequential approaches, frequent reporting omissions regarding allocation and inventory choices, and a widespread neglect of uncertainty analyses despite their importance in innovative contexts. Furthermore, scenario analyses predominantly compare different recycling pathways while neglecting alternative end-of-life options like incineration or landfilling, and rarely account for recycled material downcycling or technical substitutability. The study concludes that no clear consensus on a unified methodology exists across various industrial sectors. To enhance transparency, comparability, and decision-making utility of LCA in recycling systems, this paper outlines strategic recommendations and emphasizes the urgent need for harmonized, sector-specific guidelines.