It is time to develop characterization factors for terrestrial plastic pollution impacts on ecosystems in life cycle impact assessment – a systematic review identifying knowledge gaps

Abstract Purpose Life cycle assessment (LCA) can help evaluate the environmental impacts of processes and products over their life cycle. However, the LCA community largely agrees that current assessment methods need further development to consider plastic pollution-related impacts on ecosystems. The present review identifies the knowledge gaps that need to be filled to develop characterization factors (CFs) considering the fate, exposure, and effects of plastic pollution within different environmental compartments and implement them in life cycle impact assessment (LCIA). Methods A systematic literature review was carried out in the databases Web of Science and Scopus regarding the evaluation of plastic pollution in LCIA, followed by snowball sampling. In total, 59 relevant documents were found. Approaches regarding the modelling of fate, exposure, effects, and overall impacts were extracted, summarized, and critically analyzed to present the status of knowledge and deduct knowledge gaps. Results Fate of plastic emissions considers their redistribution between environmental compartments, fragmentation, and degradation. Several approaches have been applied to model the redistribution of macro- and microplastics in different environmental compartments, but fragmentation has not been sufficiently integrated. There is one approach we found in literature related to degradation which is widely used. Exposure and effects have been modelled for the pathways entanglement, uptake, and greenhouse gas emissions. Additionally, seabed smothering and the transport of invasive species via plastic debris have been identified as pathways but their corresponding effects have yet to be quantified. For the marine compartment, all existing knowledge has been applied to LCIA. On the contrary, for the freshwater and terrestrial compartments, knowledge from the field of risk assessment still needs to be integrated. Conclusions Knowledge is accessible for all fate processes for macro- and microplastics and has mostly been incorporated and applied to LCIA. On the contrary, not all exposure pathways have been adequately addressed. Especially for the terrestrial environment, a suitable definition of sub-compartments, a proper analysis of exposure pathways, and the translation of existing effect knowledge into EFs are lacking.