That silky, pyramid-shaped tea bag that looks fancier than the flat paper kind? It is usually plastic. And when you pour near-boiling water over it, it does not just steep your tea. It sheds.
In 2019, a team at McGill University in Montreal ran a tidy little experiment. They bought four brands of tea sold in those mesh, pyramid bags, cut them open, dumped out the leaves so the tea itself would not interfere with the measurement, rinsed the empty bags, and then steeped them in water heated to 95 degrees Celsius. That is normal brewing temperature. Then they counted what came off.
The answer, published in the journal Environmental Science and Technology by Laura Hernandez, Nathalie Tufenkji and colleagues, was staggering. A single plastic tea bag released about 11.6 billion microplastic particles and roughly 3.1 billion nanoplastic particles into one cup. The researchers confirmed with electron microscopy and infrared spectroscopy that the particles came from the bags, which were made of nylon and polyethylene terephthalate (PET, the same plastic as a water bottle).
Eleven billion is a hard number to picture. For comparison, the researchers noted that the plastic load from one of these bags was thousands of times higher than the microplastic amounts previously reported in other foods and drinks. So if you have switched to the "premium" silky bags thinking they were a nicer choice, this is the part nobody mentioned on the box.
Old-school tea bags were paper. Cheap, flat, stapled or folded shut. They work fine, but they look basic and they can impart a slight papery taste. Somewhere along the way, tea companies started using mesh pyramid bags that show off whole leaves and look more like a product you paid extra for. Those mesh bags are woven plastic, usually nylon or PET, sometimes a corn-based bioplastic called PLA.
Here is the problem with all three: heat. Plastics soften and degrade when they get hot, and a cup of tea is one of the hottest things most people drink. The bag spends three to five minutes sitting in water hot enough to make it shed particles you will never see, taste, or strain out.
Even some "paper" tea bags are not fully plastic-free. Many are sealed with a thin polypropylene coating or web so the bag holds its shape and does not fall apart in hot water. That coating is a smaller source than a full mesh bag, but it is still plastic in contact with hot liquid.
This is where honesty matters more than alarm. The McGill study proved that the particles come off in huge numbers. What it did not prove is that drinking them harms you, and the researchers were careful about that distinction.
Microplastics research is young. We know these particles are turning up nearly everywhere scientists look, including in human blood, lungs, and placentas. We have early studies showing some types of plastic particles cause inflammation or behavioral changes in fish and water fleas. But we do not yet have strong human evidence that the levels people actually consume cause specific diseases.
The World Health Organization, in a 2019 review of microplastics in drinking water, concluded that the existing evidence was limited and that there was not enough data to say microplastics in water pose a clear risk to human health at current levels. That review was about water, not tea bags specifically, but it captures the honest state of the science: real exposure, uncertain consequences. The reasonable response is not panic. It is to cut the exposure where it is easy to cut, and this one is very easy.
You do not need to give up tea. You need to give up the plastic that touches it.
A stainless infuser costs a few dollars and lasts for years. That is the whole fix for this particular exposure.
It helps to ground the headline number. Eleven billion particles sounds like the bag is dissolving in front of you, but most of those particles are vanishingly small, which is exactly why you cannot see, taste, or strain them. The microplastics counted in the McGill work spanned from a few micrometers down to the nanoscale, and the nanoplastics, the 3.1 billion of them, are far too small to register as cloudiness in the cup. Your tea looks completely normal. That is part of what makes this exposure easy to overlook.
The follow-up question researchers care about is whether those particles stay intact or shed even smaller fragments over time, since size drives how far a particle can travel in the body. A visible fleck almost certainly passes through you. A nanoparticle is small enough that scientists cannot yet rule out it crossing into tissue. The McGill team measured what comes off the bag. The harder questions about what happens next are still being worked out in labs, and that uncertainty is the honest center of this whole topic. It is also why the cheap fix is worth taking even before the science is settled. You lose nothing by switching, and you remove a concentrated source while the researchers catch up.
Tea bags are a vivid example, but they are one stream feeding a much larger flow. Microplastics reach your body through bottled water, shellfish, sea salt, dust you breathe indoors, and food packaging. Plastic that heats up, abrades, or sits in contact with food and drink tends to shed the most, which is why hot tea in a plastic mesh bag is such a clear offender.
If you want the full rundown of where these particles come from and what is known about the health questions, our guide on microplastics and our cornerstone explainer on whether microplastics in drinking water are dangerous both go deeper than we can here. And if you are trying to reduce particle exposure from your tap, a good filter matters as much as your tea bag choice. You can start by checking what is actually in your local water on our homepage.
The takeaway is simple. The science on health effects is still forming, but the fix for plastic tea bags is cheap, immediate, and costs you nothing in flavor. Switch to loose leaf or plain paper and you have removed one of the most concentrated microplastic sources from your daily routine.
### How many microplastics does a plastic tea bag release? In the 2019 McGill University study published in Environmental Science and Technology, one plastic tea bag steeped at 95 degrees Celsius released about 11.6 billion microplastic particles and roughly 3.1 billion nanoplastic particles into a single cup. The bags tested were made of nylon and PET.
### Are paper tea bags free of plastic? Not always. Many paper tea bags are sealed with a thin layer of polypropylene plastic so they hold together in hot water. They release far less plastic than full mesh bags, but if you want zero plastic, loose-leaf tea with a metal or ceramic infuser is the cleanest choice.
### Is it dangerous to drink tea from plastic bags? The 2019 study proved the particles come off in large numbers but did not prove they harm people who drink them. Microplastics research is still early, and the World Health Organization concluded in 2019 that evidence on microplastics in drinking water was limited. The cautious move is to reduce exposure where it is easy, and switching tea bags is easy.
### Which tea bags are the silky plastic kind? The mesh, see-through, pyramid-shaped bags that feel like fine fabric or netting are almost always plastic, usually nylon or PET. Flat, opaque, paper-style bags release much less. If the bag looks premium and transparent, treat it as plastic.
### Does hot water make tea bags release more plastic? Yes. Heat softens and degrades plastic, so brewing temperature is exactly when these bags shed the most. Steeping in hot water for several minutes is the worst-case condition, which is why the McGill team tested at 95 degrees Celsius.
### What is the easiest plastic-free way to make tea? Buy loose-leaf tea and brew it with a stainless steel infuser, a ceramic teapot with a built-in strainer, or a French press kept just for tea. An infuser costs a few dollars, lasts for years, and removes this exposure completely.