You probably reach for the kettle without thinking much about it. The ritual is familiar. Bag in, water over, three minutes, done.
Most of us never give a second thought to what the bag itself is made of.
A new study published in October 2026 in npj Science of Food found that plastic tea bags release between 555 and 2,498 microplastic particles into every cup.
The researchers also detected bisphenol A, better known as BPA, and plasticizer compounds in the brewed tea.
Also read: Just 10 minutes of daily exercise is linked to deeper sleep
Loose-leaf tea shed almost nothing by comparison. Bulk tea leaves released roughly 0.3 to 2.4 particles per serving, around a thousand times less than what came out of the plastic bags.
What the hot water pulls out of the bag
Researchers at Recep Tayyip Erdogan University in Türkiye tested 14 bagged tea brands against 14 loose-leaf brands. Each bag was steeped at about 95 degrees Celsius (203 degrees Fahrenheit) for three minutes, the way most people make tea at home.
The particles that broke off the plastic bags were almost all polyamide fibers, a type of nylon. That pattern is consistent with the bag material slowly degrading in hot water.
The study only counted particles larger than 100 micrometers, so smaller fragments were not included in the totals.
Also read: 6 everyday foods that may be quietly raising your LDL cholesterol
In other words, 2,498 particles per cup is likely a floor, not a ceiling.
Research on even finer nano-sized particles has already found that microplastics turn up in nearly every human brain tissue sample tested.
How the BPA exposure compares to the EFSA limit
The researchers also measured how much BPA ended up in a cup. At the high end, a single serving delivered 21.7 percent of the daily intake the European Food Safety Authority now considers tolerable.
That limit matters because it is far stricter than it used to be.
Also read: Depression may not be one illness: Scientists discover five different brain patterns
According to the European Food Safety Authority, the tolerable daily intake for BPA was tightened in 2023 by a factor of 20,000, after a review of newer evidence on immune effects.
The combined hazard score for all the chemicals measured stayed below the authority's safety threshold. But the authors flagged the BPA figure as a particular concern for pregnant women and young children, who are more sensitive to the compound.
How to tell a plastic bag from a paper one
The quickest check is the shape. Pyramid-shaped mesh bags are almost always plastic, usually nylon or PET. The classic rectangular, double-chamber bags are typically paper, though many still carry a thin plastic seal along the edges.
The same microplastic problem has turned up in other everyday kitchen items, including plastic cutting boards, which shed particles into chopped food.
Also read: 7 supplements that may interact with your blood pressure medication
The researchers recommend switching to bulk tea with a ceramic or metal infuser. That one swap removes the plastic bag from the brew, and with it the particles and the BPA that come along for the ride.
Also read: Breathing through your mouth while you sleep may be quietly harming your health
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.