The recycling of post-consumer plastics for food-contact applications is subject to stringent regulatory requirements, particularly with regard to the removal of potentially harmful non-intentionally added substances (NIAS). While polyethylene terephthalate (PET) recycling processes are already approved by the European Food Safety Authority (EFSA), there is a lack of guidance for other polymers like polystyrene (PS). This study aims to provide a scientific basis for assessing the decontamination efficiency required for recycled post-consumer PS in food-contact applications. As one of the first studies to propose a framework for PS decontamination assessment based on EFSA food-consumption data and conservative diffusion modeling, it contributes to filling this regulatory gap. First, European food-consumption data were analyzed to identify critical scenarios of the age-group-dependent intake of PS-packaged food. Based on this, a conservative migration model was applied using a one-dimensional diffusion simulation to determine the maximum allowable initial concentrations of NIAS in PS. The calculated values were then compared with published reference contamination levels to calculate the required cleaning efficiency. The combination of food-consumption values and the migration process showed that trays for fruits and vegetables are the most critical food-contact application for post-consumer PS recycling. The most stringent assumptions resulted in necessary decontamination efficiencies ranging from 92% for the smallest molecule, toluene (92.14 g/mol), to 42% for the largest molecule, methyl stearate (298.50 g/mol). The results provide a methodological basis for regulatory assessments and offer practical guidance for designing safe recycling processes, thereby supporting the circular use of PS in food packaging and building the basis for future regulatory assessments of other polymers, in line with the European Union Plastics Strategy and circular economy objectives.

Polystyrene (PS) is a widely used packaging material, but its recycling for food‐contact applications is still limited, partly due to a lack of quantitative data on the migration behavior of potential contaminants. This study investigates the diffusion behavior of organic compounds in high‐impact polystyrene (HIPS) under vacuum and controlled thermal conditions. Virgin HIPS was intentionally spiked with five organic compounds covering a broad range of molecular weights and polarities. The contaminated material was pressed to plates with various thicknesses which were then exposed to defined combinations of temperature and residence time in a vacuum oven. Initial and residual concentrations were quantified using gas chromatography, and the data were used to calibrate a one‐dimensional diffusion model based on Fick's second law including Arrhenius‐type temperature dependency. The results confirm that the model adequately describes the experimental data and allows reliable estimation of diffusion coefficients. Clear correlations were observed between the diffusion coefficients and the molecular weight, polarity, and volatility (boiling point) of the surrogates. These findings provide fundamental parameters for predicting diffusion‐driven mass transfer in HIPS processing and establish a scientific basis for future risk assessments of recycled PS in applications requiring particularly high purity standards, such as food‐contact materials.

The transition toward a circular economy for food-contact plastics requires overcoming technical and regulatory hurdles regarding material stability and safety. This study evaluates an industrial-scale mechanical recycling process for post-consumer polystyrene (PS) waste, combining advanced pre-treatment with a specialized material conversion technology. Refined pre-treatment achieves high material purity by effectively removing foreign polymers and non-food-grade articles. Although the conversion step induces measurable polymer-chemical changes, specifically rubber-phase cross-linking, the resulting post-consumer PS recyclate retains robust mechanical and rheological characteristics. This technical integrity is proven by effective decontamination of various contaminations, achieving high material purity. Furthermore, the results of challenge tests confirm that the process meets established safety requirements for contact-sensitive food packaging applications. Life cycle assessment underscores the environmental advantages of this pathway compared to virgin production. This research provides a validated blueprint for closing the loop on polystyrene through high-performance mechanical recycling.