Scientists Discover Shocking Levels of Microplastics in Popular Tea Bags

We must de-plasticize food packaging

By Universitat Autonoma de Barcelona

Plastic waste pollution poses a significant environmental challenge with serious implications for the health and well-being of future generations. A major source of human exposure to micro and nanoplastics (MNPLs) is food packaging, with ingestion and inhalation being the primary pathways of exposure.

Researchers from the Mutagenesis Group at the UAB Department of Genetics and Microbiology conducted a study to identify and characterize MNPLs released from various types of commercially available tea bags. The study found that steeping these tea bags in hot water leads to the release of large quantities of nano-sized particles and filamentous structures, representing a notable source of MNPL exposure.

The tea bags analyzed were made from nylon-6, polypropylene, and cellulose. The findings revealed that:

• Polypropylene released approximately 1.2 billion particles per milliliter, averaging 136.7 nanometers in size.
• Cellulose emitted around 135 million particles per milliliter, with an average size of 244 nanometers.
• Nylon-6 released about 8.18 million particles per milliliter, averaging 138.4 nanometers in size.

To characterize the different types of particles present in the infusion, a set of advanced analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (ATR-FTIR), dynamic light scattering (DLS), laser Doppler velocimetry (LDV), and nanoparticle tracking analysis (NTA) were used. “We have managed to innovatively characterize these pollutants with a set of cutting-edge techniques, which is a very important tool to advance research on their possible impacts on human health,” remarks UAB researcher Alba Garcia.

Interactions with human cells observed for the first time

The particles were stained and exposed for the first time to different types of human intestinal cells to assess their interaction and possible cellular internalization. The biological interaction experiments showed that mucus-producing intestinal cells had the highest uptake of micro and nanoplastics, with the particles even entering the cell nucleus that houses the genetic material. The result suggests a key role for intestinal mucus in the uptake of these pollutant particles and underscores the need for further research into the effects that chronic exposure can have on human health.

“It is critical to develop standardized test methods to assess MNPLs contamination released from plastic food contact materials and to formulate regulatory policies to effectively mitigate and minimise this contamination. As the use of plastic in food packaging continues to increase, it is vital to address MNPLs contamination to ensure food safety and protect public health”, researchers add.

Reference: “Teabag-derived micro/nanoplastics (true-to-life MNPLs) as a surrogate for real-life exposure scenarios” by Gooya Banaei, Doaa Abass, Alireza Tavakolpournegari, Joan Martín-Pérez, Javier Gutiérrez, Guyu Peng, Thorsten Reemtsma, Ricard Marcos, Alba Hernández and Alba García-Rodríguez, 16 November 2024, Chemosphere.
DOI: 10.1016/j.chemosphere.2024.143736

The study was developed under the framework of the European project PlasticHeal coordinated by, Alba Hernández lecturer in the Department of Genetics and Microbiology at the UAB. Researchers from the UAB Mutagenesis Group Alba García-Rodríguez, Ricard Marcos, and Gooya Banaei, first author of the research article, were also involved in the study, with the collaboration of researchers from the Helmholtz Centre for Environmental Research in Leipzig, Germany.