Microplastic and nanoplastic contamination in bottled water

Despite increasing reports of micro- and nanoplastic contamination in bottled water, uncertainties remain regarding standardized detection methods, chronic human health effects, and globally harmonized regulatory frameworks. This review critically synthesizes current evidence on the occurrence, analytical detection, environmental impacts, human health risks, regulatory developments, and mitigation strategies associated with micro- and nanoplastics contamination in bottled water. Microplastics primarily originate from the degradation of polyethylene terephthalate packaging and bottling processes, with additional contamination arising from source water and storage conditions. These particles, often carrying chemical additives and adsorbed pollutants, pose ecological risks by disrupting aquatic ecosystems and biodiversity. Human exposure occurs predominantly through ingestion, with bottled water consumers potentially ingesting substantially greater numbers of microplastics than tap water consumers. Smaller particles, particularly nanoplastics (<100 nm), can penetrate biological barriers, raising concerns regarding oxidative stress, mitochondrial dysfunction, inflammation, carcinogenicity, immune disruption, and bioaccumulation. Detection methods vary considerably in sensitivity, detection limits, and analytical performance, with µRaman and µFT-IR spectroscopy identified as the most reliable techniques; however, the lack of standardized analytical protocols and certified reference materials limits data comparability across studies. Reported concentrations of microplastics in bottled water vary widely among brands and geographical regions, ranging from a few to thousands of particles per litre. Overall, the available evidence indicates that widespread contamination of bottled water with micro- and nanoplastics, together with limitations in analytical standardization and human health data, represents a significant challenge for accurate exposure assessment and risk evaluation.