"I often drink tea bags"... Millions of people are drinking this.

The harmful effects of microplastics on the human body have already been recognized through numerous studies. Food packaging is one of the main routes of human exposure to microplastics and nanoplastics. This study, conducted by researchers from the Department of Genetics and Microbiology at the Autonomous University of Barcelona in Spain, analyzed commercially available tea bags in detail to determine whether they release microplastics and nanoplastics. Microplastics are plastic particles less than 5 mm in size, and nanoplastics are plastic particles less than 1 μm in size.

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 steeped in water. A variety of techniques were used to characterize the various types of particles present in the steeped water, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force transduction-four-wave infrared spectroscopy (ATR-FTIR), dynamic light scattering (DLS), laser Doppler velocimetry (LDV), and nanoparticle tracking analysis (NTA).

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

The researchers also stained these plastic particles and exposed them to various types of human intestinal cells to observe how they interacted. Their results revealed that mucus-producing intestinal cells absorbed the most micro- and nanoplastics, with some particles even penetrating the cell nucleus, where genetic material is stored. This highlights the important role that intestinal mucus plays in plastic particle absorption and highlights the need for further research into the potential health effects of chronic exposure to plastics.

“It is crucial to develop standardized testing methods to assess micro- and nanoplastic contamination released from plastic materials that come into contact with food, and to establish regulatory policies to effectively reduce this contamination,” the researchers said. “As the use of plastics in food packaging continues to increase, addressing micro- and nanoplastic contamination is essential to protect food safety and public health.”

Meanwhile, in April of this year, research results on microplastics released from disposable tea bags were announced in Korea. The Seoul Metropolitan Government Health and Environment Research Institute measured microplastics in empty tea bags after removing the contents from 20 tea bags and brewing them according to the drinking instructions on each product. As a result, regardless of the material of the tea bag, polypropylene was the most abundant at 85.7%, and those with a size of 50-99㎛ were the most abundant at 42.9%. In particular, when tea bags were left in water while drinking the tea, 2-4 times more microplastics were detected than when brewed according to the drinking instructions on the product, so the research team recommended removing the tea bags immediately after brewing according to the drinking instructions on the product.