Characterizing the heterogeneous contamination of commercial paper and board food packaging at different scales

Assessing the contamination of paper and board (P&B) food packaging materials poses significant challenges due to the sensitivity limits of analytical methods and the low precision of sampling processes. This study aims to enhance the understanding of P&B food packaging contamination by investigating the distribution of contaminants at different scales using a combination of chromatographic and spectroscopic techniques. A total of 36 substances were targeted, including phthalates, photoinitiators, and bisphenol A. Key findings reveal that intra-packaging variability can lead to concentration variations by a factor of 2-7. Recycled materials generally exhibit higher contamination levels, with concentrations of certain contaminants reaching up to 700 mg/kg. Microscopy, including confocal laser scanning microscopy (CLSM) and Raman micro-spectroscopy, enabled the identification and differentiation of contaminants, highlighting specific marker molecules and characteristic Raman bands. The study underscores the necessity of comprehensive sampling strategies, advocating for the grinding of entire packaging to obtain representative samples. The introduction of contamination "fingerprints," based on occurrences and correlations between concentrations, offers a promising approach for hazard identification and risk assessment. Overall, the findings contribute to the development of safer and more sustainable food packaging solutions, emphasizing the need for improved analytical techniques and standardized sampling methods in the context of increasing use of recycled materials.