An effect factor for macro- and microplastic ingestion impacts on marine ecosystems for use in life cycle assessment

Plastic debris ingestion poses a significant and increasing threat to marine biodiversity and ecosystem health. Despite the increasing evidence of its prevalence and severity, plastic ingestion impacts remain limited in widely adopted environmental assessment tools such as Life Cycle Assessment. To fill this gap, we propose a global effect factor to quantify the potentially affected fraction of species (PAF) impacted by macro- and microplastics ingestion in marine air-breathing vertebrates (marine mammals, seabirds, and sea turtles). We gathered population-level ingestion prevalence data from peer-reviewed literature and databases for stranded and bycaught individuals across various regions worldwide. Based on the locations where species have been observed, we estimated their exposure to marine plastic debris by delineating species ranges across eight major ocean basins. Species-specific dose-response relationships were then developed and used to construct a field-based species sensitivity distribution, from which a global effect factor was derived. The results shows that the concentration that affects 20 % of species above a threshold of 10 % plastic ingestion prevalence within their populations (HC20_EC10) is 51.7 kg/km³, resulting in a global effect factor of 3.87E-03 PAF km³/kg. A sensitivity analysis on modeling assumptions and parameters revealed that the derived effect factor remained consistent in the order of magnitude. Our study contributes to the understanding of plastic ingestion in marine ecosystems and provides a critical step for integrating their potential physical effects as an impact pathway in Life Cycle Assessment, allowing plastic ingestion to be considered alongside other environmental stressors in sustainability assessments.