From freshwater to drinking water and fish

Microplastics (MPs), defined as plastic particles ranging from 1 µm to 5 mm, have emerged as ubiquitous environmental contaminants due to the widespread use and persistence of plastics. They originate both from the degradation of larger plastic debris and from intentionally produced small particles. MPs have been detected across environmental compartments, including freshwater systems, and even within the human body, raising concerns about potential exposure and risks. This thesis aimed to investigate the occurrence of MPs in freshwater environments and related consumption products, specifically drinking water and fish, while contributing to the advancement of reliable analytical methodologies. Pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS) was employed as the primary analytical technique due to its ability to provide size-independent, quantitative, and polymer-specific data. Complementary use of micro-Fourier transform infrared spectroscopy (µ-FTIR) enabled particle-based characterization. Urban surface water in Amsterdam was analyzed across seasons and locations, revealing higher MP concentrations in summer and in densely urbanized canals. Polypropylene (PP) and polyethylene (PE) were the dominant polymers, and MP concentrations were positively correlated with suspended particulate matter. In drinking water systems, raw water contained relatively high MP concentrations, while treatment processes achieved removal efficiencies of 97–98%. Consequently, tap water contained only trace levels of MPs. Methodological challenges, particularly background contamination, highlighted the importance of strict quality control. The occurrence and potential accumulation of MPs in Nile tilapia were also investigated. Low concentrations were detected in fillet tissues, with heterogeneous distribution across samples. A controlled exposure experiment demonstrated minimal translocation of MPs into edible tissues, with most particles being excreted, suggesting limited human exposure through fish consumption. Overall, this thesis provides mass-based evidence of MP occurrence across environmental and biological matrices and demonstrates the applicability of Py-GC-MS for robust MP quantification. The findings contribute to improved methodological standardization and enhance the understanding of MP distribution and potential human exposure pathways.