Tea bags and hidden plastics

Tea is one of those small daily rituals people rarely question. You boil the water, drop in the bag, wait a few minutes, and drink.

But the bag itself is worth a closer look. Over the last decade, a lot of the "silky" pyramid-shaped tea bags on grocery shelves stopped being paper. They are made of plastic mesh, usually nylon or PET.

That matters, because hot water is very good at pulling particles out of plastic.

What the McGill study actually found

In 2019, researchers at McGill University tested four brands of premium plastic tea bags. They cut each bag open, rinsed out the tea leaves so they would not confuse the count, and then steeped the empty bag in near-boiling water for a few minutes, the way you would at home.

Under an electron microscope, they counted what came out.

A single plastic tea bag released roughly 11.6 billion microplastic particles and about 3.1 billion smaller nanoplastic particles into one cup of hot water ^[1].

That is not a typo. Billion, into a single cup.

To put the number in context, the researchers pointed out this was thousands of times higher than the amount of plastic previously reported in other foods and drinks. Not because tea is uniquely dirty, but because the bag itself is the source, and hot water accelerates the release.

Follow-up work has since confirmed the basic finding across other plastic tea bag types, including newer plant-based plastics like PLA ^[2].

Why heat matters so much

Plastics do not really "dissolve." But they do soften, swell, and shed at the surface when heated. The higher the temperature, the more mobile the polymer chains become, and the easier it is for tiny fragments to break off.

We covered this pattern in more detail in What happens when food and drinks are heated in plastic and Your kettle, your coffee, and microplastics. Tea bags sit right in the middle of that story. You are essentially bathing a piece of plastic in water at about 195 to 210 degrees Fahrenheit, then drinking the water.

Cold brew, by comparison, releases far fewer particles from the same bag. Heat is doing most of the work.

Are paper tea bags safe then?

Mostly yes, but with an asterisk.

Traditional paper tea bags are made from a blend of cellulose fibers. On their own, they are fine. The catch is the seal. Many "paper" tea bags are held shut with a thin band of plastic, usually polypropylene, so the bag does not fall apart in hot water. Others use a heat-sealed thermoplastic layer along the edges.

So when you shop, it is worth checking the box. Brands that use fully plastic-free bags tend to say so on the packaging, sometimes noting a plant-based starch seal or a folded and stapled design instead.

If in doubt, the safer bet is to skip the bag entirely.

The simplest swap

Loose leaf tea plus a stainless steel infuser is probably the cleanest, cheapest, and honestly the tastiest option.

A small mesh infuser costs a few dollars, lasts basically forever, and gives the leaves room to unfurl, which most tea drinkers will tell you improves the flavor. Glass and ceramic infusers work just as well. Any material that is not plastic and not treated with a plastic coating is a step forward.

A few practical notes:

• If you love the convenience of bags, look for ones explicitly labeled plastic-free, unbleached, and heat-sealed without polypropylene.
• Skip anything described as "silky," "silken," "nylon mesh," or "pyramid" unless the brand specifically states it is plant-based and plastic-free. Even plant-based bioplastics like PLA still shed particles in hot water ^[2].
• Rinsing the bag first does not really help. The particles come from the bag itself, not from surface dust.

Where Winnow fits in

Tea bags are a good example of why exposure reduction is a practical exercise, not a purity project. You can make a real dent by changing a few kitchen habits, and it costs almost nothing to do. We wrote more about that mindset in Why personal solutions still matter in a systemic problem.

At the same time, no one drinks only filtered water and brews only loose leaf tea. Modern life includes plastic contact you cannot fully avoid, from packaging to food processing to the air itself.

That is the gap Winnow was designed for. Our probiotic blend is shown in laboratory testing to bind micro- and nanoplastics. It is not a replacement for the small swaps at home. It is the steady support layer underneath them, a kind of gut armor for the exposures you cannot see or plan around.

Change the bag. Keep the ritual. The tea itself was never the problem.