The Tea on Microplastics

By Kate Huckstep, class of 2019

Microplastics have been getting a lot of attention lately, as more and more of them are found in our oceans, rivers, air, and soil. Very recently, scientists have discovered yet another – somewhat surprising – location abundant with microplastics: a good old cup of tea.

Morning Tea: Picture by katiew via Flickr

What Are Microplastics?

Microplastics, technically speaking, are tiny particles of plastic between 100nm and 5mm in size. So, you know, we’re looking at stuff that can be as small as one thousandth the width of a single hair. These plastic particles can be really super-duper tiny and are often not visible to the human eye.

Microplastics can be categorised as either Primary or Secondary microplastics. Primary Microplastics are just microplastics which were that small to begin with. An example of this is something called a “nurdle”; one of the small plastic pellets that gets melted down to make pretty much all of our larger plastic materials. These are also used in their tiny solid pellet form in some exfoliating facial scrubs. Many countries are beginning to ban this practice, however.

Then, there are our Secondary Microplastics. These are the microplastics that were formed when bigger plastics began to degrade in to smaller and smaller parts. These are the most common microplastics found polluting our waterways, or, leeching into our food.

Microplastics: Picture by Chesapeake Bay Program via Flickr

But how did these get into my tea!? 

Well, technically, this is not the fault of the tea but the teabag. While most teabags are made of natural fibres, they’re often reinforced or sealed by plastic. Some companies have even moved to entirely plastic-based “silken” teabags as their standard. All of these plastics are “food-grade”, of course, however even food-grade plastics can begin to disintegrate at 40°C. So, you can see how this might be an issue for a product designed to be steeped in boiling water, right?

In the study published just last week in the Journal of Environmental Science and Technology, the researchers essentially did the following:

They took four different brands of plastic teabag, emptied out the tea and washed them, then steeped the bags in 95°C water for 5 minutes. They then analysed the chemical composition of the water using spectroscopy and electron microscopy; basically allowing them to look closely at the water samples on a molecular level.

Image from Hernandez et al. “Plastic Teabags Release Billions of Microparticles and Nanoparticles into Tea.” Environmental science & technology (2019).


Not only did they find a staggeringly large number of microplastic particles in the water, the type of plastic they found matched the chemical composition of the type of plastics used in the tea bags. So, they concluded that the teabags were responsible for releasing around 11.6 billion microplastics into the water.

To put this into perspective, the previous estimate for how many microplastics we consume each year was approximately 50,000. At the time, this study acknowledged it was likely an underestimate. This recent study on tea reveals just how much of an underestimate it may actually be!

Is this bad? What does this mean for my health?

We don’t actually have any strong evidence (yet) that consuming these microplastics is directly harmful for human health. Unfortunately, we also don’t have convincing evidence that they’re totally safe, either.

The problem with eating (or drinking!) plastics is that they often contain chemicals which closely resemble hormones. When animals ingest these hormone mimics, it has the potential to confuse the body and lead to a bunch of health issues like reproductive problems or liver issues.

Another issue is that microplastics are very good at absorbing and carrying toxins, due to their relatively great surface area and the fact that they’re hydrophobic – meaning, they don’t dissolve in water. There is evidence that microplastics can accumulate in various tissues of the marine life consuming them, and that they bring the additional toxins along for the ride!

There is good news, though. If the microplastics from our teabags are just going straight into our cup of tea, and then into our mouths, they’re not likely to be carrying additional toxins.

This doesn’t mean they’re completely safe, however.

Loose Leaf Tea: Image by Trevor Huxham via Flickr

My suggestion would be that if you’re concerned about the potential health risks of consuming large quantities of microplastics, maybe stay away from teabags and stick to good old fashion loose-leaf tea!


If you liked this article, Kate also runs a podcast with their brother called Curiosity Killed the Rat. Check them out on Instagram and in Apple Podcasts and Spotify.