Integrating LDIR Spectroscopy for Assessing Exposure to Microplastics in Drinking Water: A Preliminary Study

MP contamination in drinking water is an emerging public health concern, yet standardized analytical workflows and exposure assessments remain limited and fragmented. This study provides an exploratory assessment of MP exposure through drinking water, combining particle-resolved analysis with consumption-based estimates. Laser Direct Infrared (LDIR) spectroscopy was applied within the analytical workflow to characterize MPs across different drinking water supply types. Ten drinking-water samples (five bottled, two tap, two public dispensers, and one office dispenser) were analyzed within a 10–500 µm size window, and particle-resolved results were combined with a consumption survey to support preliminary exposure estimates. MPs in the 10–150 µm range were detected in six of ten samples, while tap waters and all blanks were particle-free, supporting analytical robustness. Bottled waters showed the highest MP abundances (6–148 particles L−1) and mass concentrations (0.03–22.4 µg L−1). Particle-size distributions were right-skewed and dominated by particles ≤ 30 µm. PET, PU, PA, and ABS predominated, consistent with packaging and dispensing origins. EDI estimates for bottled-water consumers ranged from 0.1008 to 0.3023 µg kg-bw−1 day−1 across three consumption scenarios (1–3 L day−1). Despite the limited sample size, the results support LDIR for source discrimination and exposure screening, providing a basis for future research.