Plastic is commonly used for food packaging, of which plastic polymer polyethylene terephthalate (PET) is widely used in the food and beverage industry. Furthermore, PET is the most suitable and recyclable plastic polymer used in food contact applications due to its functional properties: inertness and low diffusion of gases and migrants. However, using recycled PET (rPET) for food contact applications requires that the rPET is chemically safe. In this study, we use mass spectrometry and spectroscopy-based methods to characterize the chemical composition of virgin PET (vPET) and rPET. The mass spectrometric analysis demonstrated more peaks in rPET and the spectroscopic analysis revealed degradation of the rPET after the recycling process. The tentatively identified peaks in both vPET and rPET were mainly PET oligomers. The present work suggests the importance of testing PET obtained from one or more recycling processes to evaluate the effect on the polymer properties, chemical migration, and chemical safety of rPET for food contact.

Polycyclic aromatic hydrocarbons (PAHs) are present in smoked food products. More toxic nitrated (NPAH) and oxygenated (OPAH) PAHs derivatives are found concomitantly to PAHs and are therefore believed to be found in smoked food products. However, only a few PAH analyses on food include these derivatives. We adjusted and successfully validated a GC-QTOFMS method including 13 NPAHs and 2 OPAHs as well as the 4 regulated PAHs for analysis of 14 smoked (13 fish and one bacon) and one pan fried fish samples.OPAHs were detected in the highest concentrations in 13 of 15 samples. Non-target screening revealed the presence of an additional four OPAHs and two methylated PAHs. Future food analysis should, based on these results, focus on PAH and oxygenated derivatives.

Microplastics (MPs) are carriers of persistent organic pollutants (POPs). The influence of MPs on the toxicokinetics of POPs were investigated in a feeding experiment on Atlantic salmon (Salmo salar), in which fish were fed similar contaminant concentrations in feed with contaminants sorbed to MPs; feed with virgin MPs and contaminated feed (1:1); and feed with contaminants without MPs. The results showed that the salmon fillets accumulated more POPs when fed with a diet where contaminants were sorbed to the MPs, despite the 125-250 μm size MPs themselves passing the intestines without absorption. Furthermore, depuration was significantly slower for several contaminants in fish fed the diet with POPs sorbed to the MPs. Modelled elimination coefficients and assimilation efficiencies of lipophilic chlorinated and brominated contaminants correlated with contaminant hydrophobicity (log K_ow) within the diets and halogen classes. The more lipophilic the contaminant was, the higher was the transfer from feed to salmon fillet. The assimilation efficiency for the diet without MPs was 50-71% compared to 54-89% for the contaminated MPs diet. In addition, MPs caused a greater proportional uptake of higher molecular weight brominated congeners. In the present study, higher assimilation efficiencies and a significantly higher slope of assimilation efficiencies vs log K_ow were found for the Cont. MPs diet (p=0.029), indicating a proportionally higher uptake of higher-brominated congeners compared to the Cont. diet.. Multiple variance analyses of elimination coefficients and assimilation efficiencies showed highly significant differences between the three diets for the chlorinated (p=2E-06; 6E-04) and brominated (p=5E-04; 4E-03) congeners and within their congeners. The perfluorinated POPs showed low assimilation efficiencies of <12%, which can be explained by faster eliminations corresponding to half-lives of 11-39 days, as well as a lower proportional distribution to the fillet, compared to e.g. the liver.