In a research article published on May 11, 2021, in the peer-reviewed Journal of Hazardous Material, Ying-Jie He and colleagues from Yunnan University, Kunming, China, provide an overview on intentionally added substances (IAS) as well as on non-intentionally added substances (NIAS, FPF reported) and microplastics (MPs) migrating from microwavable plastic food containers (MPFCs) to evaluate potential exposure to humans.
The scientists selected 15 popular MPFCs made of polypropylene (PP), styrene-acrylonitrile copolyester (SAN), or Tritan and performed chemical migration experiments according to standard procedures for testing plastic food contact materials in the European Union (FPF reported), including microwave heating. In total, they identified 42 IAS and over 100 NIAS using ultra high performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF/MS). Identified NIAS included Cramer class III toxic compounds such as the antioxidant Irgafos 168 OXO (CAS 95906-11-9), previously observed in migrates of polypropylene films (FPF reported), as well as isomers of hexadecanamide and oleamide. For some MPFCs, the concentration of these compounds exceeded the threshold at which they are estimated to be of toxicological concern. However, the application of the MPFCs to a 2nd and 3rd migration step suggests that repeated ethanol treatment before application can reduce the migration of chemicals to levels complying with regulation. In addition, the researchers quantified the MPs migrating into distilled water upon microwave heating. Individual samples contained more than one million particles per liter, but MP levels varied strongly across the respective samples. Based on the experimental data, the study found that the consumption of take-out food once a day “might result in an annual intake of IAS/NIAS up to 55.15 mg and 150 million MPs particles.”
The authors conclude that there is a “significant gap in the available experimental data used to evaluate the comprehensive hazards and risks” of MPFC products and that “reliable risk assessments both of chemicals and MPs should be based on actual data in future research.”
He Y.-J. et al. (2021). “Migration of (non-) intentionally added substances and microplastics from microwavable plastic food containers.” Journal of Hazardous Materials (published online May 11, 2021)