Scientists from Recep Tayyip Erdoğan University tested 14 brands of bagged tea and 14 brands of loose-leaf tea—including both black and green varieties—purchased from supermarkets in Turkey. The findings were published in the journal npj Science of Food.
Of the 14 brands of bagged tea, only four used plastic bags made of polyamide (a type of nylon), while the remaining 10 were made of paper or cellulose. The tea bags were steeped in freshly boiled water for three minutes, after which the number of particles was counted.
The plastic tea bags released between 555 and 2,498 particles per cup. In contrast, loose-leaf tea contained only about 0.3–2.4 particles per cup—likely introduced from the environment, agricultural processes, or manufacturing equipment.
This is a cause for concern, as growing evidence suggests that microplastics are not as harmless as once thought. Laboratory studies have indicated that they can trigger inflammation and expose the body to reactive radicals, as well as to bisphenol A (BPA) and phthalates.
Unsurprisingly, detectable levels of BPA and phthalates were found in all the plastic-bagged tea samples tested by the researchers. In one brand—which was not named in the study—there was a notable spike in the phthalate BBP; the researchers believe this originated from the adhesive used to seal the tea bag. Bisphenol A (BPA) and phthalates are man-made chemicals often added to plastic products to enhance their flexibility, transparency, strength, and durability. They are referred to as “ubiquitous chemicals” because they can be found—well, everywhere in the environment, including within the bodies of a wide variety of wild animals and humans.
Growing evidence suggests that these harmful chemicals can have a serious impact on animal health, particularly on the endocrine system—a network of glands that produce hormones regulating metabolism, sexual function, reproduction, sleep, mood, and much more.
The good news is that BPA levels were found to be within safe limits. According to standards set by the European Food Safety Authority, a single cup of tea contained between 4.5% and 21.7% of the tolerable daily intake for BPA—a figure the authors note is worth paying attention to, especially for children, pregnant women, and heavy tea drinkers.
Previous research has indicated that the scale of microplastic contamination from tea bags is far, far greater. One study published in 2019 suggested that synthetic tea bags could contaminate a cup of tea with billions of micro- and nanoplastic particles.
The new study identified a much smaller number of particles—ranging from hundreds to several thousand per cup—though this figure is likely an underestimate. The research team used a method incapable of detecting nanoplastics and only identified particles larger than 100 micrometers as plastic; therefore, the actual number could be significantly higher than what was reported.
About the Author
