Research has shown that when brewing tea with tea bags, millions of micro- and nanoplastics (MNPLs) can be released and enter the body.

It has already been known through various studies that microplastics have harmful effects on the human body. Food packaging is one of the main routes through which humans are exposed to micro- and nanoplastics. In this study conducted by researchers from the Department of Genetics and Microbiology at the University of Barcelona in Spain, the release of micro- and nanoplastics from commercially available tea bag products was analyzed in detail. Microplastics refer to plastic particles with a size of 5 mm or less, while nanoplastics are plastic particles smaller than 1 μm.

 

The tea bags used in this study were confirmed to be made of nylon-6, polypropylene, and cellulose polymers. The researchers observed the release of micro- and nanoplastics when these were soaked in water and brewed. In this study, various techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), dynamic light scattering (DLS), laser Doppler velocimetry (LDV), and nanoparticle tracking analysis (NTA) were used to characterize the different types of particles present in the brewed water.

Analysis results showed that during the tea brewing process, polypropylene releases approximately 1.2 billion particles of an average size of 136.7 nanometers per milliliter, cellulose releases about 135 million particles of an average size of 244 nanometers per milliliter, and nylon-6 releases 8.18 million particles of an average size of 138.4 nanometers per milliliter.

 

Additionally, the research team stained these plastic particles and exposed them to various types of human intestinal cells to observe the interactions. The results showed that mucus-producing intestinal cells absorbed the most micro- and nanoplastics, and some particles penetrated into the cell nuclei containing genetic material. This highlights the important role of intestinal mucus in absorbing plastic particles and emphasizes the need for further research on the potential impacts on human health due to chronic exposure to plastics.

 

The researchers stated, "Developing standardized testing methods to assess micro- and nano-plastic pollution released from plastic materials in contact with food is very important, as well as establishing regulatory policies to effectively reduce such pollution." They added, "As plastic use in food packaging continues to increase, it is essential to address the issues of microplastic and nanoplastic pollution to ensure food safety and protect public health."

 

Meanwhile, in April of this year, research results on microplastics released from disposable tea bags were also announced domestically. The Seoul Metropolitan Institute of Health and Environment examined 20 tea bag products by measuring microplastics in empty tea bags after removing the contents, following the brewing instructions indicated on each product. As a result, the detected microplastics were predominantly polypropylene at 85.7%, regardless of the material of the tea bag, and the most common size was 50-99㎛ at 42.9%. In particular, when tea bags are left in water while drinking tea, the amount of microplastics detected was 2 to 4 times higher than when brewed according to the instructions on the product, leading the researchers to recommend removing the tea bag immediately after brewing as indicated.