Towards a harmonized framework of social life cycle assessment for bio-based value chains: A systematic review and stakeholder mapping

The bioeconomy is promoted as a pathway to sustainability, yet its social performance remains insufficiently understood, particularly given persistent concerns about inequality, labour exploitation and uneven institutional capacity across global value chains. Social Life Cycle Assessment (S-LCA) offers a framework for assessing these issues, but methodological fragmentation undermines its usefulness for decision-making in bio-based systems. This study investigates whether a standardized approach to S-LCA is emerging in the bioeconomy literature and how stakeholders are represented across value chains. A systematic review of 44 peer-reviewed S-LCA case studies, conducted using the STARR-LCA protocol, was combined with Principal Component Analysis of stakeholder data to map patterns and gaps in stakeholder inclusion. The results show partial convergence around certain elements, such as the notably widespread use of UNEP/SETAC impact subcategories and consistent assessment of farmers and agricultural workers in upstream stages. Yet reveal substantial heterogeneity in functional units, system boundaries, impact subcategory selection and impact assessment methods. Stakeholder coverage is strongly biased towards upstream workers, with researchers, consumers and waste workers largely overlooked, and multifunctional circular systems rarely addressed. These inconsistencies limit the reliability of cross-study comparisons and the capacity of S-LCA to guide evidence-based policy. The study advances a mixed-methods approach for diagnosing fragmentation and argues for broadening stakeholder inclusion, extending system boundaries beyond cradle-to-gate, and establishing clearer methodological conventions to create a more coherent and policy-relevant tool for governing the bioeconomy transition.