In an article published on November 12, 2024, in the peer-reviewed Journal of Hazardous Materials, Selina Tisler and co-authors from the University of Copenhagen, Frederiksberg, Denmark, compared the migration of non-volatile chemicals from reusable plastic bottles of various polymer types.
The scientists studied 16 reusable bottles manufactured in different countries and made of polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polycyclohexylenedimethylene terephthalate glycol- modified (PCTG), polyethylene terephthalate glycol-modified (PETG), tritan (a BPA-free copolyester), ecozen (a bio-based copolyester), and silicone.
After washing the bottles, the researchers performed migration experiments with tap water for 24 hours in the dark at approximately 21 °C. Subsequently, they concentrated the water containing the migrants and measured samples using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-ESI-QTOF-MS/MS) for a non-targeted analysis. In addition to this non-targeted analysis, the authors measured the presence of selected chemicals by performing so called suspect screening, using a list of > 10,000 small molecules compiled by Schymanski et al. (FPF reported). Furthermore, they estimated the levels of newly identified compounds without analytical standards employing quantitative structure-property relationships (QSPR).
Tisler and co-authors reported that each bottle type had a unique chemical fingerprint, as they displayed a set of detected chemical features (which are a proxy for migrating chemicals); 80% of these chemical features were only found in one but not the other 15 bottles. However, bottles made of the same polymer type showed “minimal overlap” with regards to their chemical features. Chemical migration was highest from the silicone bottle, followed by HDPE, LDPE, and PP bottles. 60% of detected features came from silicone migrates, of which 97% could not be identified. “HDPE and LDPE bottles had heterogenic compound patterns with no correlation between bottles of the same material,” but partial correlation was observed for PP bottles.
Nearly 1000 compounds could not be identified. Taking a closer look at the identified compounds, silicone migrants included phthalates and plasticizers, while PP bottles released light inhibitors, clarifying and coating agents, as well as bisphenol A derivates.
Evaluating the hazard based on the identified and quantified chemicals, the authors ranked silicon, PP, and PE as the highest risk. PS, PET, PETG, and PCTG ranked at the other end of the spectrum with the fewest migrating chemicals (6% of all features). Although migration was the lowest from Ecozen bottles, the chemicals included were concerning ones. In addition, clear bottles performed better than colored bottles due to the reduced leaching of colorants.
The authors concluded that a comprehensive assessment of plastic products is essential to protect consumers. Furthermore, given “the significant variability in chemical compositions across different bottle types and materials, …the establishment of effective and equitable regulations” is complicated.
Previously, Tisler and co-authors reported on the migration of 400 plastic-related compounds from reusable sports bottles and found dishwashing to increase migration (FPF reported).
Reference
Tisler S. et al. (2024). “Chemical migration from reusable plastic bottles: Silicone, polyethylene, and polypropylene show highest hazard potential in LC-HRMS analysis.” Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2024.136391
