European legislation allows non-intentionally added substances (NIAS) to be present in plastic food contact materials (FCMs) but the manufacturers must ensure the safety of the NIAS. However, assessment of NIAS represents a challenge for industry and the scientific community due to a missing harmonized methodology, as well as the lack of hazard data and outdated regulatory guidelines (FPF reported). A recently published review evaluated analytical techniques for the non-targeted screening of NIAS migrating from FCMs and came to the conclusion that in addition to chemical analysis, bioassays should be incorporated into the risk assessment of NIAS (FPF reported). Bioassays allow researchers to analyze the toxicity of chemical mixtures migrating from plastics and other FCMs (FPF reported). Also the International Life Sciences Institute’s (ILSI) guidance document on the risk assessment of NIAS in FCMs recommends bioassays to characterize the hazards of unidentified NIAS (FPF reported).
In alignment with the ILSI guidance document, Maricel Marin-Kuan from the Société des Produits Nestlé SA-Nestlé Research, Lausanne, Switzerland, and co-authors developed a protocol for the risk assessment of can coating materials during product research and development by combining chemical and biological screening of migrants. In their article published on February 7, 2023, in the journal Toxics, they present the outcome of an inter-laboratory study that evaluated the validity and reproducibility of the protocol’s methods. Global food and coatings manufacturers and three contract research laboratories with expertise in migration experiments, analytical chemistry, and in vitro bioassays, collaborated in the study.
For the assessment metal cans with an epoxy-based coating were produced which were assumed to induce endocrine and genotoxic activities. The prepared samples were analyzed by three laboratories which were instructed to follow the protocol in performing migration experiments, chemical analysis using liquid chromatography–high-resolution mass spectrometry (LC-HRMS), and bioassays to test for endocrine activity (nuclear receptor binding activities), genotoxicity, and mutagenicity (Bluescreen™ HC test, and MiniAmes test).
The authors reported that “the inter-laboratory chemical analysis and bioassay results displayed acceptable consistency between laboratories, but technical differences led to different data interpretations.” The factors which impacted the quality of the data the most and, therefore, also led to the greatest discrepancies in the results were found to include differences in the equipment used for sample preparation and in chemical analysis (e.g., different mass spectrometers), in the techniques applied (e.g., to control for contamination), and in the choice of the applied cytotoxicity test. Marin-Kuan and co-authors plan to continue developing the protocol to make it more robust to the variation in standard lab equipment and other identified inconsistencies. Overall the study identified that “harmonization between laboratories for packaging safety assessment of intentionally added substances and NIASs” is crucial to reduce laboratory variability and to improve consistency.”
Reference
Marin-Kuan, M. et al. (2023). “Interlaboratory Study to Evaluate a Testing Protocol for the Safety of Food Packaging Coatings.” Toxics. DOI: 10.3390/toxics11020156
