By: Becca Yeamans & Lewis Perdue
We’ve talked about microplastics quite a bit recently. If you’re curious about any of our previous coverage, check out the following links for more on; microplastics in disposable plastic cups, how to prepare black peppercorns to reduce microplastic exposure, how to choose a pepper grinder for reduced microplastic exposure, as well as a couple of mechanistic articles on how microplastics get into our food to begin with, and the health implications of ingesting micro- and nano-plastic particles.
Just when you think you’ve covered all of it, another product crosses your desk that turns out to be yet another culprit in your daily exposure of microplastics. Today, we’ll be talking about tea bags.
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Yes, tea bags. Those seemingly innocuous little sachets of herbs and leaves sitting there steeping in your cup of hot water for your afternoon tea. (I am drinking a cup of tea right now as I write this, in fact!). While many styles of tea bag are made of paper, there is an increasing number of brands switching to a plastic-based tea bag, which could be problematic from both a health and an environmental perspective.
Today, I wanted to share a study published in 2019 in the journal Environmental Science & Technology, which aimed to evaluate whether or not these plastic tea bags leach micro- and/or nano-plastics into hot water when brewing tea.
Brief Summary of Methods
4 different kinds of commercially-available (in Montreal, Quebec) tea were used for this study. Each of the teas were individually wrapped in plastic tea bags. Each teabag was cut open and the tea leaves removed. The bags were then washed three times. Reverse osmosis water (contaminants removed) was added to glass vials at heated to 95oC. Empty teabags were then added and “steeped” for 5 minutes. After this, the steeped water was transferred to a new, clean glass vial for analysis.
Electron microscopy was used to visually evaluate micro- and nano-plastics.
Appropriate negative and positive controls were also tested.
In addition to determining the micro- and nano-plastic content of the steeped water, toxicity tests were also performed. The organism that was used for this toxicity test was Daphnia magna, a water flea. Basically, tiny organisms were exposed to the steeped water and mobility as well as survival was noted.
Metal tests were also performed on the steeped water.
Highlighted Results
- After analysis, the researchers calculated that if someone were to drink a cup of tea made using the teabags tested in this study, they could be consuming around 2.3 MILLION micro-plastics (greater than 1μm in size), 14.7 BILLION “submicron”-plastics (less than 1μm in size), and 3.1 BILLION nano-plastic particles (less than 100μm in size) per cup.
- 21% of the submicro-sized plastic particles were nano-sized plastic particles.
- Out of the 4 types of teabags analyzed, 2 of them were found to be made up of nylon-6,6, while the other two were found to be made up of PET.
- Analysis confirmed nylon-6,6 and PET to be in the steeped water of each respective vial after testing.
- Knowing the estimated concentration of micro-, submicro-, and nano-plastics as well as what each teabag was made up, the researchers estimated that someone drinking a single cup of tea with these teabags could be consuming 13-16μg of micro- and nano-plastic particles.
- It should be noted that one of the controls tested were teabags that were not cut open, and those also showed significant micro- and nano-plastic particle concentrations, meaning that the act of cutting the bags wasn’t the reason why the micro- and nano-plastic particles were getting into the water.
- Researchers also tested the effect of the heating of the water as well, and they found that the heating process (to 95oC) yielded significantly more micro- and nano-plastic particles in the steeped water than room temperature water.
- In fact, the heated steeped water had 300x MORE micro- and nano-plastic particles than the room temperature steeped water. So, heating the teabags definitely did something to change the structure of the teabags to allow more micro- and nano-plastic particles to leech out into the steeped water.
- In terms of toxicity, no deaths of the D. magna were observed. However, there were changes in their swimming behavior/mobility after a few days exposure to the steeped water compared to those that were not exposed.
- While water fleas are NOT humans, they are organisms that are often used in toxicity experiments and can give a hint as to whether or not there is reason for testing toxicity further in other organisms.
- There were no metals found in the teabags themselves, though it is known and some were found to be in the tea leaves independent of what kind of teabag they are in.
Conclusions
According to the results of this study, the researchers found that the potential amount of micro- and nano-plastics someone could consume in a single cup of tea is several orders of magnitude greater than the highest levels reported thus far in other foods.
Playing with math some more, the researchers calculated that if the 159 million tea drinkers in the United States were to drink tea only packaged in plastic tea bags, then there would be somewhere around 1.9 to 4.6 TONS of micro- and submicron-plastic particles consumed. Additionally, throwing away the teabags would generate more plastic waste, something that we definitely don’t need more of these days!
What Can YOU Do?
Well, this one is relatively simple. In order to reduce your micro- and nano-plastic particle intake when it comes to teabags, simply avoid plastic teabags all together! If you’re not sure what the teabags are made of, consider getting a metal (stainless steel) tea ball and purchase loose leaf tea only. Using loose leaf tea in a reusable metal tea ball will not only keep teabag-associated micro- and nano-plastic particles out of your body, but the amount of waste you generate will also decrease, since you will no longer be tossing away used disposable tea bags.
Want to read more on the subject? Here is the link to the study presented today, as well as other resources for your reading pleasure (note: you may only have access to the abstracts on some of these articles linked):
Further reading:
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