Editorial: “Unravelling micro-/nano-plastics toxicity profiling: can we link associated effects to intrinsic characteristics?”

Micro-and nanosized plastic particulates (MNPs) are a diverse group of synthetic substances recognized as an increasing environmental problem (MacLeod et al. 2021, Weis and Alava 2023). Due to the heterogenic nature, with respect to emission pathways, particle size, polymer type and interactions with other environmental chemicals, this substance group requires novel approaches to better understand the diverse range of impacts on ecosystem health (Beggel et al. 2025, Koelmans et al. 2022). For a sound risk and impact assessment, it is essential to gain more knowledge on their environmental transport, fate and degradation behavior. Data gaps particularly key to be tackled include processes that determine MNPs bioavailability and exposure scenarios towards biota as well as the application of meaningful test endpoints that allow the characterization of the variety of potential effects, especially on the sublethal level. This research topic highlights four manuscripts that exemplarily cover the latest scientific developments and findings on the toxicology of micro-and nanoplastics exposures with specific focus on new test-methods and approaches allowing for a sensitive and in-depth environmental fate and effect assessment.The first manuscript, "Modeling marine microplastic emissions in Life Cycle Assessment: Characterization factors for biodegradable polymers and their application in a textile case study", by Pellengahr et al. (2025) integrates primary experimental data and modelling approaches to determine the fate factors of biodegradable polymer fibers released from textiles. The authors demonstrated that the derived characterization factors are only applicable for physical effects on biota, largely due to data availability, while acknowledging that degradation products of certain polymers can result in toxic effects. Thus, the study also highlights the further need for including plastic additive leaching in effect studies, and the consideration of degradation rates in sediments to fill existing knowledge gaps and improve characterization factors for life cycle impact assessment (LCIA).The second manuscript, "From the ocean to our kitchen table: Anthropogenic particles in the edible tissue of U.S. West Coast seafood species", by Traylor et al. (2025), highlights the complexity of identifying artificial particle sources in aquatic environments. The study provides proof that commercially valuable finfish can be a potential source of particle exposure to humans via food. It is further highlighted that the focus on model species may under-represent the effects on wild species or environmentally relevant MNP concentrations, which may mis/over-represent effects. exchanges along trophic chains and within food-webs and, thus, their long-term associated effects. 62Currently there is a growing understanding that the complexity of MNPs in the environment needs to 63 account for the variety of particle characteristics (polymer type, size, morphology, hydrophobicity, 64 density, and a growing list of other relevant attributes) and the degradation (weathering) stage, and 65 cannot be limited to a small number of model organisms. To advance our understanding of MNP 66 toxicity and apply this knowledge to risk and impact assessment, future research must move beyond 67 controlled laboratory settings and embrace ecologically realistic approaches that reflect 68 environmental complexity, long-term and multi-stressor effects. Integrating interdisciplinary 69 collaborations and innovative methodologies will be key to link the intrinsic characteristics of these 70 particles to their ecological consequences.