Assessment of micro- and nanoplastics release from food packaging under simulated use conditions: challenges and analytical strategies

, Cella Claudia, La Spina Rita, Mehn Dora, Valsesia Andrea, Fumagalli Francesco Sirio, Gilliland Douglas.

The anthropogenic release of micro- and nanoplastics is an emerging issue since these particles constitute a ubiquitous and growing pollutant which not only threatens the environment but may have potential consequences for human health. In particular, there is concern about the release of secondary micro and nanoplastics from the degradation of plastic consumer products. The phenomenon is well documented in relation to plastic waste in the environment but more recently there have been reports of microplastic generated during the normal use of plastic food contact materials such as water bottles, tea bags and containers. Unfortunately, understanding these events is hindered by the lack of harmonized analytical methods in the field. In this study, we demonstrate that microplastics breakdown occurs during the normal use of polyethylene rice cooking bags and ice-cube bags, as well as from nylon teabags. Methods developed for the analysis of microplastics in environmental samples were explored as the starting point for identification and quantification of micro and nanoplastics coming from food contact materials. Our method includes testing particle release under conditions that mimic their intended use, by applying heat, microwaves, freeze-thaw or immersion in boiling water. A critical step is sample preparation - by lyophilisation or filtration - to concentrate particles on functionalized surfaces enabling the chemical recognition. Raman and Fourier-Transformation InfraRed (FT-IR) microscope technologies were applied to identify plastics as well as any other material coming from the packaging, such as dyes or food residues. Finally, mixtures of potassium bromide (KBr) and plastic particles were prepared to create pellets and perform FT-IR measurements. Integration of specific peaks in the FT-IR spectra allowed to build calibration curves and to quantify the mass of micro- and nanoplastics release from the packaging materials.

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