Everyday storage and handling of PET bottled water increase human exposure to nano- and microplastics: Influence of socio-economic factors

This study quantified the release of nanoplastics and microplastics (NMPs) from single-use polyethylene terephthalate (PET) water bottles under real-world storage and handling conditions and examined how socio-economic factors influence exposure behaviors. Eight leading U.S. bottled water brands were tested under high temperatures (60 °C), mechanical shaking (200 rpm), and 15-day temperature cycling to simulate storage in vehicles or outdoors. The highest release occurred under combined heat and shaking, where nanoparticle concentrations increased by 9.29-fold and microparticles also rose significantly. Prolonged freeze - thaw and high temperature cycling also significantly elevated nanoparticle concentrations, though microparticle release was less consistent. Raman spectroscopy identified PET, polyethylene, and polypropylene particles originating from both bottle body and caps. Surface degradation, rather than bulk changes, was the likely driver of particle release, as supported by differential scanning calorimetry showing heating-induced aging without increased release. A statewide survey (n = 1673) in Nebraska revealed that individuals with higher awareness of microplastics and higher education levels were less likely to consume bottled water or store it under heat, underscoring the role of knowledge and behavior in shaping exposure risks.