Consult the tea leaves, and you’ll find… microplastics!

By now you’ve probably heard about the islands of plastic in our oceans— collections of Styrofoam, grocery bags, soda bottles, and other reminders of how excessive use and improper disposal of plastic is leaving a stain on our planet. But, did you know that most of the plastic in the ocean is not readily identifiable? Rather it’s in the form of small, microscopic particles that are released when plastic and synthetic fibers break off and break down from their original use items, such as laundry, straws, and… teabags!

Microplastics in tea?

A group of researchers from McGill University, led by Laura Hernandez, recently sought to determine if plastic (synthetic fabric) tea bags released microplastics into tea while it’s brewing. An examination of four different commercial brands of synthetic tea bags found the bags to be composed of two main types of plastic fibers: nylon and polyester terephthalate (or “PET”; what’s used to make most polyester clothing, such as activewear). The research team cut the tea bags open, removed the tea leaves, and washed the remaining bag fragments thoroughly to remove any fragments of tea and/or plastic released from cutting.  To simulate the conditions of tea steeping, the team submerged each teabag in a glass container of near-boiling purified water. After “steeping” the used tea bags and the steeping water were evaluated under a high-powered microscope. Before steeping, the tea bags had, what appeared to be, fine particles on their surfaces. These particles disappeared after steeping, and cracks and dents were then present in the bag fibers, indicating that there was some damage being done to the plastic fibers. Upon examination of the steeping water, the researchers found particles on the micro- (1 millionth of a meter!) and nano- (1 billionth of a meter!) size range. The analysis of the chemical makeup of these particles, revealed them to be microplastics and nanoplastics of nylon and/or PET—the same as the parent tea bags. From the particles counted in a small sample size and the fraction of the total amount of steeping water it represented, the team calculated that the steeping process released billions of these particles! Similar experiments yielded significantly fewer particles when steeping tea in cold water, which led the researchers to conclude the temperature of the water was a big contributor to this particle release. Although the research team did not disclose the brand names of the tea bags they tested, they found similar results between brands, indicating that their findings can be broadly applied to all plastic tea bags.

Steeping plastic tea bags release billions of microplastics and nanoplastics into your tea. Reprinted with permission from Hernandez et al. Copyright 2019 American Chemical Society.
What harm is there?

If the thought of ingesting billions of plastic particles is a bit unsettling to you, you’re not alone. The research team sought to evaluate the toxic effects that these teabag scraps might have on living systems.

Daphnia magna is a small, freshwater crustacean that is commonly used in biological research and as commercial fish food. Source.

The team steeped several tea bags in hot water to create a concentrated solution, and then exposed Daphnia magna (D. magna) to the solution.D. magna is a type of crustacean found in freshwater that is often used as a model species for biological research. The concentration of the steeping solution these creatures were exposed to is equivalent to drinking a cup of tea every other day for a year. The researchers found that the micro and nanoparticles seemed to alter the carapace (outer shell) of these critters and cause them to swim strangely… both of which have bad implications for their ability to survive in the wild. These creatures are a long way from humans, so it’s not recommended to make direct comparisons or draw too many conclusions from this finding. However, D. magna are an important part of the food web, and they are a first step to more complex toxicity studies.


Good news! Microplastics are not necessarily in your tea’s future

Worried about how microplastics will have to impact your calming or caffeinating drinks? Don’t be! The researchers showed that the micro- and nano- plastics just come from the plastic bags, not the tea itself. Plastic particles thus can be avoided by using paper bags and/or loose tea leaves with a reusable metal steeper. As is the case with other plastic pollution, minimizing the use of single-use plastic is key. Be a thoughtful consumer and keep your environmental footprint in mind while shopping—it can help your health as well as that of the environment!



Source Article: L. M. Hernandez, E. G. Xu, H. C. E. Larsson, R. Tahara, V. B. Maisuria, & N. Tufenkji. Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea. Environ. Sci. Technol.2019, 53, 21, 12300-12310.

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Mary Davis

I earned my PhD in Chemical Engineering from Princeton University in 2018, where my research focused on nanoscale polymer systems and how their properties change with geometry. I am now applying my background in polymers to environmental systems. This involves studying the breakdown of plastics and plastic byproducts in the environment, as well as their interactions with other pollutants. When I’m not working in the lab, I enjoy crafting, cooking, and being outside.

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