This proposal refers to the use of high-resolution mass spectrometry (HRMS) coupled to Pyrolysis gas chromatography-mass spectrometry (Pyr-GC-ToF) for the analysis of NPs in aqueous matrices. Unprecedented detection capabilities will be obtained due to the combination of HRMS and membranes/filters acting as sample support, thereby allowing the identification of particle sizes at environmentally relevant concentrations (below 0.1 µg/L level). The proposal will also explore the knowledge gap currently existing on the dynamics of the disintegration processes that generate of plastic particles under the effect of environmental stressors. Finally, the project will also study the potential toxicity of NPs derived from bioplastics as recent evidence indicates that biodegradable not always means safe for the biota as well as the chemical risks posed by leaching of additives during the slow degradation process of plastics in nature and sorption/desorption of co-occurring chemicals