Terrestrial characterization factors for bio- and fossil-based plastics: microplastics ingestion and additives...

Only a few works have contributed to quantifying the potential impacts of mismanaged plastics at the end-of-life stage. The MarILCA working group has developed characterization factors (CFs) to include the aquatic compartment, however, the terrestrial compartment remains a methodological gap. This work contributes to the quantification of the potential impacts of polypropylene (PP) and low-density polyethylene (LDPE) as well as their potential market substitutes plastic biopolymers (BPs) (PHA- and PLA-based) in the terrestrial compartment. Emission-based CFs have been developed to quantify their impacts through physical effects on biota related to microplastic ingestion, and ecotoxicological effects due to additives release. Fate factors (FFs) were derived from Plastic Footprint Network data and studies on accelerated photooxidation, the primary degradation pathway in the terrestrial compartment. Effect factors (EFs) were developed by the USEtox recommendations based on literature data on the physical and ecotoxicological impacts related to microplastics ingestion and additives release. An exposure factor (XF) of 1 was applied, as the CFs integrate potential impacts without distinguishing between short- and long-term effects. The study found that additives pose a greater environmental risk than microplastics ingestion, with CFs 3 to 4 orders of magnitude higher in the terrestrial compartment and even higher in the aquatic compartment. It is, therefore, essential to consider both the terrestrial and aquatic compartments to understand the impact of plastic pollution comprehensively. Finally, the study also found that the CFs of BPs are close to petrochemical plastics, underling the importance of proper waste management for the environmental performance of BPs.