Drinking tea may expose individuals to plastic pollution. It has been revealed that tea bags sold in the market contain micro or nanoplastics.
Researchers from the Autonomous University of Barcelona (UAB) analyzed microplastics or nanoplastics originating from various types of tea bags and published their results in the international journal "Chemosphere" on the 20th (local time). Microplastics are defined as particles smaller than 5 mm, while nanoplastics are primarily in the nanometer (nm, one billionth of a meter) range.
The material of tea bags is mainly paper, but plastics such as polyamide (nylon), polypropylene (PP), polyethylene terephthalate (PET), and polylactic acid (PLA) are also used. The researchers analyzed the plastic released when brewing tea with tea bags made from nylon, polypropylene, and cellulose polymers.
The analysis revealed that polypropylene tea bags released approximately 1.2 billion particles per milliliter (mL) of water during the brewing process, with an average particle size of 136.7 nm. Considering that the water capacity of tea is over 100 mL, this means that more than 120 billion micro and nanoplastics are released in a single cup of tea.
Alba Garcia, a researcher at UAB, noted, "We successfully characterized contaminants using advanced technology." The cellulose tea bags released about 135 million particles per mL, with an average size of 244 nm. Nylon tea bags released 8.18 million particles per mL, with an average particle size of 138.4 nm.
The researchers also dyed the plastic particles and observed their interactions with various types of human intestinal cells. The results showed that mucus-producing intestinal cells absorbed the most micro and nanoplastic particles, with some particles even entering the nucleus, which contains genetic material. This indicates that intestinal mucus plays a significant role in the absorption of plastic particles in the body, and chronic exposure to plastics may affect human health.
The researchers emphasized the importance of developing standardized testing methods to evaluate micro and nanoplastic pollution released from plastic packaging and establishing regulatory policies to effectively reduce pollution. They noted, "Given that plastic use in food packaging continues to increase, it is crucial to address micro and nanoplastic pollution for food safety and public health."
It has been confirmed previously that tea bags can induce plastic damage to the human body. In 2019, researchers at McGill University in Canada reported in the American Chemical Society's "Environmental Science & Technology" that when one tea bag was placed in water at 95 degrees Celsius, 11.6 billion microplastics and 3.1 billion nanoplastics were detected.
In South Korea, a study on microplastics from tea bags was also announced in April. The Seoul Institute of Health and Environment investigated microplastics released when 20 tea bags were submerged in hot water after removing their contents. Similar to the findings of the Spanish researchers, the predominant microplastic detected was polypropylene, regardless of the tea bag's material.
In particular, when the tea bag is left in the cup throughout the drinking process, 2 to 4 times more microplastics are detected compared to brewing tea as indicated on the product label, and even microplastics like polyester that were previously undetected appear over time. The Seoul Institute of Health and Environment recommended, "To reduce exposure to microplastics, it is advisable to brew tea according to the label instructions and remove the tea bag immediately."
Reference materials
Chemosphere (2024), DOI: https://doi.org/10.1016/j.chemosphere.2024.143736
Seoul Institute of Health and Environment (2024), https://sihe.seoul.go.kr/archives/554214
Environmental Science & Technology (2019), DOI: https://doi.org/10.1021/acs.est.9b02540