Mechanical stress causes microplastic release from PET mineral water bottles

Plastic particle ingestion has become of concern as a possible threat to human health. Previous works have already explored the presence of microplastic (MP) in the bottled drinking water as a source of MP intake. Here, we consider the release of MP particles from single-use PET mineral water bottles upon exposure to mechanical stress utilizing scanning electron microscopy (SEM), which allows the implementation of morphological and elemental analysis of the plastic material surface and quantification of MP concentrations in sample water. The aim of this study is to better evaluate the sources of MP intake from plastic bottles, especially considering the effect of daily use on these bottles such as the abrasion of the PET and PE material. For that, we analysed MP release of PET-bottlenecks and PE-caps on their surfaces after a series of bottle openings/closings (one time, ten times, 100 times). Furthermore, we will investigate the occurrence of MP particles on the inner wall surface of the PET bottles and measure MP concentrations of the water after exposing the bottles to mechanical stress (squeezing treatment; none, one minute, ten minutes). All investigated bottles were purchased in Italian supermarkets and included different brands and water types. An in-house manufactured filtration apparatus was used to filter the sample water. To assess sample contamination or particle loss during the procedure in the lab, blank and positive control samples were included. The first results show a considerable increase of MP particles occurrence on the surface of PET and PE material (bottleneck and caps) after opening and closing the bottles 100 times. Considering these findings, MP concentrations in the bottled mineral water are expected to increase after exposure to mechanical stress (squeezing treatment). More information about MP concentration in mineral water - possibly increased through release of particles from the bottle inner wall - will be presented in the conference. In addition to the implications of the results, also the applicability of the used filtration and analysis technique will be discussed.