Tea Bags Without Microplastics: What 2 Studies Found — and Which Bag Types Are Safe

Every tea drinker has heard the warning: plastic tea bags release microplastics when you steep them. But most of the advice stops there, leaving you to guess whether your current bag is the dangerous kind or a reasonably safe one.

Two peer-reviewed studies put numbers on the difference. The gap between bag types isn't small — it's orders of magnitude. Here's what the research actually says, and which bags to choose instead.

What the Research Actually Says

Study 1: McGill University (2019)

The first study to quantify the release came from researchers at McGill University in Montreal. They steeped nylon and PET (polyethylene terephthalate) pyramid-style tea bags at 95 °C — a realistic tea temperature — and counted the particles released into the water.

Their finding: a single plastic pyramid bag released approximately 11.6 billion microplastic particles and 3.1 billion nanoplastic particles per cup. The study was published in Environmental Science & Technology in 2019 and has since been cited hundreds of times.

Study 2: University of Almería (UAB 2024)

A 2024 study from the University of Almería went further by comparing multiple bag materials head-to-head: polypropylene (PP), nylon-6 (polyamide), and cellulose (paper). Researchers steeped each type under standardized conditions and measured particle counts per milliliter of tea.

The results were published in Chemosphere and showed a dramatic difference based on material alone:

The cellulose bags in the UAB study released ~135 particles per mL — but these were cellulose fibers, not synthetic plastic particles. The health implications of cellulose particles are considered far less concerning than petrochemical-derived plastic, which is what the EPA and WHO assess when discussing microplastic exposure risks.

Which Tea Bags Release the Fewest Microplastics?

Based on the available research, bag materials rank in this order from lowest to highest release:

1. Stainless steel or glass infuser with loose-leaf tea — zero plastic shed from the brewing vessel
2. Unbleached cellulose (paper) bags — ~135 cellulose particles/mL; no synthetic plastic
3. Nylon-6 flat bags — ~8.18 million particles/mL (far lower than PP, still significant)
4. Polypropylene flat bags — ~1.2 billion particles/mL
5. Nylon/PET pyramid bags — ~11.6 billion particles/cup at 95 °C

The problem with reading the label

Many bag manufacturers don't disclose materials on the package. The most common unlisted plastic is polypropylene — a thin, heat-sealable film used to seal the edges of paper-looking bags. If you tear open a tea bag and the outer mesh or seal has a slight sheen, it likely contains plastic. Fully paper bags (like those used by some traditional brands) have a matte, fibrous texture throughout and crinkle rather than stretch.

How to Make Tea Without Microplastics

Switching doesn't have to mean giving up convenience. The two lowest-exposure methods are straightforward:

Option 1: Loose-leaf in a stainless steel infuser

This is the gold standard. Buy loose-leaf versions of the teas you already drink, and use a fine-mesh stainless steel ball or basket infuser. No plastic touches your hot water at any point. Stainless infusers cost $5–15 and last years. Quality loose-leaf tea is often cheaper per cup than bagged tea from the same brand.

Option 2: Unbleached cellulose paper bags

If you prefer the convenience of bags, look for unbleached paper bags from brands that explicitly confirm their bags are cellulose only — no plastic sealant on the edges, no nylon mesh window. The bag should feel fully matte and papery, not smooth or shiny.

What about compostable bags?

Some brands market bags as "compostable" or "biodegradable." This generally means the bag is made from PLA (polylactic acid), a corn-starch-derived bioplastic. PLA still sheds particles when steeped in hot water and is not the same as paper. Look for bags explicitly labeled cellulose or paper — not just compostable.

Why Does Bag Material Matter So Much?

The mechanism is straightforward: heat degrades plastic. At near-boiling temperatures (90–95 °C), polymer chains in nylon and polypropylene break apart at the surface, releasing fragments into the water. The faster a material degrades thermally, the more particles it sheds per steep cycle.

Cellulose, the material in paper bags, is also a polymer — but it's a natural one (wood-pulp fibers). The human gut processes cellulose routinely, and it doesn't accumulate in tissue the way synthetic petrochemical plastics do. The WHO's 2019 microplastics report specifically identifies synthetic polymers (polyethylene, polypropylene, nylon, PET) as the particles of greatest concern for human health — not natural cellulose.

The EPA similarly focuses its microplastics health assessment on petrochemical-derived particles and the chemical additives (plasticizers, stabilizers, colorants) they can carry. Natural fiber particles don't carry the same chemical load.