MarILCA characterization factors for microplastics, tire particles and cellulosic fibers in life cycle assessment: the PEBBLE method for regionalized physical impacts in marine, freshwater and terrestrial ecosystems

Worldwide, 10 to 40 million tons of microplastics (MPs) are emitted annually into the environment, redistributing across environmental compartments and affecting organisms. Current life cycle impact assessment (LCIA) methods partially account for their impacts on ecosystem quality by considering a limited number of compartments and particles. This study advances the work of the MarILCA group by introducing the PEBBLE method which integrates physical effects of MPs, tire and road wear particles (TRWPs), and cellulosic microfibers across environmental compartments into life cycle assessment (LCA). Characterization factors (CFs) are developed for 10 conventional polymers, 6 biodegradable polymers, 6 cellulosic materials, and TRWPs, for multiple shapes and sizes. Particle fate is modelled using the SimpleBox object-oriented (SBoo) model for microparticles, computing fate factors (FFs) in air, terrestrial, freshwater, and marine environments at continental and global scales, following USEtox regionalization. SBoo was improved to account for size and shape effects, refined degradation data, regional marine currents, and biofouling. FFs are combined with exposure and effect factors in water, sediments, and terrestrial environments to obtain updated CFs. Uncertainty is quantified using Monte Carlo simulation, and time-horizon-dependent CFs are computed. Results are provided for different LCIA methods: for IMPACT World+ and ReCiPe, CFs representing regional species loss are derived, while for GLAM, the Global Extinction Probability is applied to derive CFs representing global species loss. The results support environmental decision-making for plastics and their alternatives, and aim to be the consolidated version of MarILCA CFs for microparticles, ready for implementation in LCA tools and methods.