Microplastic Release from Drinking Water Contact Materials: Material-Specific Responses to Chlorination and Implications for Consumer Exposure

Microplastics are increasingly recognized as contaminants of emerging concern in drinking water, highlighting the need to assess drinking-water-contact materials as potential sources of particle release. This study investigated microplastic migration from six materials commonly used in drinking water infrastructure under chlorinated and non-chlorinated conditions using three consecutive migration cycles. Particle abundance, polymer composition, and size distribution were determined by micro-Fourier transform infrared spectroscopy (μ-FTIR). Microplastic release was strongly dependent on material composition. Polyester-derived particles predominated in M1 and M2, polyethylene particles in M3 and M4, and PVC particles in M5, whereas the cementitious lining material (M6) exhibited the lowest release potential. Chlorination influenced particle release in a material-dependent manner, with M2 showing the highest concentrations under chlorinated conditions. Across all materials, most particles belonged to the 20-50 μm and 50-100 μm size classes. Consumer exposure was assessed using a Relative Microplastic Release Index (RMRI), identifying M2 and M5 as the major contributors to potential exposure and M4 and M6 as the most stable materials. Overall, the results demonstrate that material composition governs microplastic release and should be considered when evaluating drinking-water-contact materials and consumer exposure.