Microplastics in Tea Bags: How Many You're Drinking and What to Use Instead

The 2019 study that changed the picture

In 2019, Hernandez et al. published a study in Environmental Science & Technology that became one of the most widely cited findings in microplastics research. The team steeped single-use plastic and nylon tea bags at normal brewing temperature (95°C) and analysed the water.

The result: a single plastic tea bag releases approximately 11.6 billion microplastic and 3.1 billion nanoplastic particles per cup. To put this in context, that is orders of magnitude higher than the concentration found in bottled water — which itself is considered a high-exposure source.

The primary polymers identified were nylon-6 and polyethylene terephthalate (PET) — the same materials used to make the mesh bags themselves. The particles were not coming from the tea or the water; they were coming from the bag disintegrating under heat.

Follow-up research confirms the finding

A 2024 study in Food Chemistry examined multiple polymer types used in tea bags and confirmed that releases exceeding one billion particles per bag are consistent across nylon-6, polypropylene, and PET bags. The study found that particle release was significantly higher at brewing temperatures than at room temperature, and increased further with steeping time — meaning the common habit of leaving a bag in the cup while drinking compounds the exposure.

Both studies found that the particles released were predominantly nanoplastics — particles below 1 micron — which are considered more concerning than larger microplastic particles because they can more readily cross biological barriers including the gut wall and the blood-brain barrier.

Are paper tea bags safe?

Not automatically. Many paper tea bags are sealed with a thin strip of polypropylene to hold the bag closed under heat. These bags release fewer particles than full plastic mesh bags, but are not particle-free. The safest paper bags are those with a staple or folded seal — no plastic adhesive — and these do release negligible particle counts by comparison.

The key distinction is between the mesh body of the bag and the seal. A paper bag with a polypropylene heat seal will release far fewer particles than a full nylon mesh bag, but more than a paper bag with a staple or fold.

How to identify plastic tea bags

The easiest test: hold the empty bag up to light. Plastic mesh bags (nylon, PET) are slightly translucent and have a smooth, silky texture. Paper bags feel rougher and are opaque. If you are unsure, check the brand's packaging — many now specify "plastic-free" explicitly in response to consumer pressure.

Brands that have committed to plastic-free bags include several major UK and European tea producers. Many supermarket own-brand bags, however, still use plastic mesh or polypropylene-sealed paper.

The practical solution

Loose-leaf tea brewed in a stainless steel or glass infuser eliminates this exposure pathway entirely. The particle release from loose-leaf tea prepared this way is negligible. For those who prefer bags for convenience, paper bags with a staple or folded seal — verified as plastic-free — are a significant improvement over plastic mesh bags.

For daily tea drinkers using plastic bags, this is one of the single largest controllable microplastic exposure sources — comparable in magnitude to microwaving food in plastic containers. The fix is both cheap and simple.

How this compares to other exposure sources

Cox et al. (2019) estimated that the average American ingests between 74,000 and 121,000 microplastic particles per year from all sources. A daily plastic tea drinker adds approximately 4.2 billion particles per week from tea alone — dwarfing most other individual exposure pathways. Switching to loose leaf or staple-sealed paper bags reduces this to near zero.