First evidence of microplastics in bottled water sold in Mexico

Given that Mexico is one of the world's leading consumers of bottled water per capita, this study provides the first evidence of microplastic contamination across ten widely consumed commercial brands in the country. A total of 2,358 MP particles were detected with an average concentration of 39.3 ± 14.6 particles/L. Statistical analysis (ANOVA, p = 0.0008) confirmed significant differences in MP levels between brands, likely attributed to variations in the production process and packaging quality. Fibers were the predominant shape of the detected MPs (72.2 %), and transparent particles were the most frequent color (57.7 %). Crucially, most detected MPs were smaller than 500 µm (80.3 %), raising toxicological concerns due to the high probability of systemic translocation in human tissues. Furthermore, FTIR spectroscopy confirmed that PET (66 %) and PP (18 %) were the dominant polymers, indicating that fragmentation and abrasion of the bottle and caps are the primary sources of MPs. The estimated intake assessment revealed that children are the most vulnerable population segment (228.2 particles/kg/year), exhibiting the highest relative MP dose normalized by body weight. Given the global evidence of adverse health effects from these polymers and their leached chemical additives, these findings underscore the urgent need to implement effective strategies to minimize MP exposure in bottled water.