First assessment of occurrence, characteristics and human exposure of microplastics in bottled drinking water, Nepal

The global increase in plastic consumption has resulted in widespread environmental contamination, yet data on microplastic (MPs) in drinking water from developing regions remain inadequate. This study presents the first comprehensive assessment of MPs in bottled drinking water across Nepal’s mountain, hill, and Terai regions with its exposure assessment. A total of 35 samples (1 L each, in triplicate) were examined using a stereomicroscopy for visual enumeration and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy for polymer identification. MPs were detected in all samples; totaling 4136 items (mean 118.17 ± 64.31 items/L). Fiber-shaped MPs dominated (71.76 %), followed by fragments (26.03 %) and films (2.87%), with transparent particles being most common. Particles ≃10 μm were most prevalent (44.82 %), and none exceeded 1 mm. Polyethylene terephthalate (PET) and polyethylene (PE), were dominant polymers, suggesting that MP contamination likely arises from both airborne or textile derived fibers introduced during bottling and handling, as well as mechanical abrasion of packaging materials. Estimated daily intake values were highest for adult women (10.53 ± 3.16 items/kg/day) and adult men (8.62 ± 2.59 items/kg/day), suggesting potential chronic exposure through bottled water consumption. These findings provide a baseline for understanding microplastic exposure in Nepal and underscore the need for standardized monitoring, improved bottling hygiene, and inclusion of MPs in national drinking water quality assessments. Future research should evaluate toxicological risks and explore mitigation strategies targeting both environmental and packaging related sources to reduce human exposures.