LC-HRMS Technology Used to Track Chemical Migration in Reusable Plastic Bottles

Researchers from the University of Copenhagen (Denmark) have developed a broad screening strategy using evaporation enrichment and liquid chromatography high-resolution mass spectrometry (LC-HRMS) to evaluate migration of non-volatile chemicals from various reusable plastic bottles. Their findings highlight the need for comprehensive assessments of plastic materials to improve consumer safety. A paper based on this research was recently published in the Journal of Hazardous Materials (1).

Global demand for reusable food packaging has increased, mostly due to increasing support of efficiently using natural resources (2). The market for reusable plastic beverage containers has grown, resulting in the development of products that are more durable for everyday use (3), as well as wide variety of plastic materials, as food contact materials (FCMs) are produced from different monomers and co-monomers (4). These monomers undergo chemical processes involving the addition of various intentionally added substances (IAS) to form polymers. Chemicals can migrate not only from the polymers themselves, but also from packaging components, such as inks, sealants, and coatings, which contribute to the complexity of substances migrating into food. Among the common classes of substances detected in food are polymer additives such as plasticizers, slip agents, stabilizers, antioxidants, unreacted monomers, and processing agents. FCMs, therefore, can have a high chemical complexity, with more than 12000 IAS as well an even higher number of previously uncharacterized, non-intentionally added substances (NIAS) detected (5).

The University of Copenhagen study analyzed a wide range of materials, revealing significant variability in chemical profiles across different bottle types. More than 70% of nearly 1000 unknown compounds were unique to specific bottles. Silicone, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) bottles showed the highest migration rates, with silicone releasing the most unknowns, but also phthalates and plasticizers. PP bottles exhibited concerning migration of clarifying agents and bisphenol A derivatives. In contrast, polystyrene (PS), polyethylene terephthalate (PET), polyethylene terephthalate glycol-modified (PETG), and polycyclohexylenedimethylene terephthalate glycol-modified (PCTG) had minimal migration, indicating lower health risks (1).

This study emphasizes that current compound classes used for evaluating especially PP and silicone bottles are insufficient, the authors wrote. They report a low correlation between country of origin and chemical diversity, with high variability across bottles. Clear bottles were preferred due to reduced colorant leaching. The authors wrote that their study demonstrates the advantages of broad screening approaches to pinpoint materials with high chemical migration. However, for a comprehensive risk assessment, they conclude that established limit values are necessary, as they are still lacking due to the absence of detailed toxicity information, leaving toxicity assessments largely reliant on predictions (1).

Transparent fresh drink water in plastic bottle. © airdone - stock.adobe.com

References

1. Tisler, S.; Kristiansen, N.; Christensen, J. H. Chemical Migration from Reusable Plastic Bottles: Silicone, Polyethylene, and Polypropylene Show Highest Hazard Potential in LC-HRMS Analysis. J. Hazard Mater. 2024, 480, 136391. DOI: 10.1016/j.jhazmat.2024.136391

2. Coelho, P. M.; Corona, B.; ten Klooster, R.; Worrell, E.Sustainability of Reusable Packaging–Current Situation and Trends. Resour. Conserv. Recycl: X 2020, 6, 100037. DOI: 10.1016/j.rcrx.2020.100037

3. Greenwood, S. C.; Walker, S.: Baird, H. M.; Parsons, R.; Parsons, Mehl, S.; Webb, T. L.; Slark, A. T.; Ryan, A. J.; Rothman, R. H. Many Happy Returns: Combining Insights from the Environmental and Behavioural Sciences to Understand What Is Required to Make Reusable Packaging Mainstream. Sustain. Prod. Consum. 2021, 27, 1688-1702. DOI: 10.1016/j.spc.2021.03.022

4. Kato, L. S.; Conte-Junior, C. A. Safety of Plastic Food Packaging: The Challenges about Non-Intentionally Added Substances (NIAS) Discovery, Identification and Risk Assessment. Polymers 2021, 13 (13), 2077. DOI: 10.3390/polym13132077

5. Groh, K. J.; Geueke, B.; Martin, O.; Maffini, M.; Muncke, J. Overview of Intentionally Used Food Contact Chemicals and Their Hazards. Environment International 2021, 150, 106225. DOI:10.1016/j.envint.2020.106225