## 5 Conclusions  
PET does not contain intentionally added BPA. However, trace contaminations may be introduced via the rPET content because BPA is ubiquitously present. Diffusion modeling is a tool to predict the migration of BPA into PET-packed food. Diffusion coefficients and activation energies of diffusion were derived from migration kinetics into food simulants at different temperatures. From this, the migration of BPA into food can be calculated down to levels in the low ng/kg food range or even below if the concentration in the rPET is known, which, in fact, can be measured. Furthermore, conversely, maximum concentrations in PET can be calculated, which correlate with such low levels, thus opening up an option to indirectly control these low levels in the PET itself. The current SML of BPA of 50 \(\mathrm{\SIUnitSymbolMicro g}\)/kg food can never be exceeded because the corresponding concentrations in rPET would need to be unrealistically high (around 9600 mg/kg assuming storage for 365 days at 25 \({}^{\circ}\)C, predicted with the experimentally determined \(\mathrm{E_{A}}\) and \(\mathrm{D_{0}}\) from 20% ethanol kinetic). The new proposed threshold limit of 1 \(\mathrm{\SIUnitSymbolMicro g}\)/L [22] will allow maximum concentrations of BPA in the bottle wall of 296 mg/kg (3% acetic acid), 254 mg/kg (10% ethanol), and 191 mg/kg (20% ethanol). These maximum concentrations are far above the BPA concentrations measured between 2019 and 2023. Therefore, also, the new proposed threshold limit cannot be exceeded. On the other hand, however, the new TDI of 0.0002 \(\mathrm{\SIUnitSymbolMicro g}\)/kg bw/d and a corresponding maximum migration level of 0.012 \(\mathrm{\SIUnitSymbolMicro g}\)/kg food for a 60 kg person is more challenging. From the results of this study, it can be concluded that maximum BPA concentrations of 3.57 mg/kg (3% acetic acid), 3.06 mg/kg (10% ethanol), and 2.30 mg/kg (20% ethanol) in PET bottle walls intended for food contact for up to 365 d at 25 \({}^{\circ}\)C are in compliance with the maximum migration level of 0.012 ug/kg. These maximum values are borderline with the experimentally determined BPA concentrations in rPET. However, the planned prohibition on intentionally added BPA in food packaging will probably have a positive effect on the concentrations of BPA in rPET, most probably resulting in (significantly) lower concentrations of BPA in rPET-containing beverage bottles. The monitoring of BPA in rPET over the next few years will show whether this reduction of the BPA concentration in rPET bottles was unique or is a trend. The monitoring of BPA in rPET initiated with this study can now be continued after the ban on BPA and will show to what extent legal measures have an impact on non-intentionally added BPA in rPET. The applied method for the determination of BPA described in this paper was found suitable for quantification in rPET. The detection limits are low enough, and the method can be used for the quality assurance control of recyclates. The BPA concentrations determined in this study provide an overview of how much BPA can be determined in commercial beverage bottles with recyclate content. As expected, the concentrations in the investigated 375 bottles show a broad variation. Under given migration conditions, the migration of BPA into the beverage is directly proportional to the concentration of BPA in the PET bottle wall. In order to minimize the migration of BPA, the concentration in the bottle wall can be minimized. The study confirms that prediction of the diffusion coefficients according to the E\({}_{A}\)-based model and the resulting migration calculations of BPA from PET into food match very well with the experimental results. In contrast, the A\({}_{P}\) model was confirmed to be highly overestimative in comparison with the experimentally determined migration into food simulants. Finally, BPA should be minimized in rPET, which would require precise knowledge of the entry route of BPA into the rPET cycle.