The disguise
Tea is leaves and water — the most innocent-looking habit in the pantry. The bag is the problem, and I’ve written this one up in full: Your Tea Bag Is Probably Plastic — and Hot Water Sets It Loose. This page is the summary card.
The plastic
Three variants. “Silken” pyramid bags: woven nylon or PET mesh. Standard paper bags: heat-sealed with ~2–3% polypropylene fibre. “Plant-based” bags: PLA — still a polymer.
The evidence
One silken bag at brewing temperature released ~11.6 billion microplastics plus ~3.1 billion nanoplastics into a single cup (McGill, ES&T, 2019) lab. The polymer comparison: PP teabags ~1.2 billion particles/mL, cellulose ~135 million/mL, nylon-6 ~8.2 million/mL — and the particles entered human intestinal cells, reaching the nucleus (UAB, Chemosphere, 2024) lab.
Newer nuance worth having: a 2025 study tracked particles over time — synthetic-bag particles stayed stable for days, while cellulose-bag particles shed in bigger numbers initially but biodegraded within about a week, with no toxicity to cultured gut cells at tested doses (Polymers, 2025) lab. The material of the particle matters, not just the count.
The tell — and the fix
Shiny pyramid = plastic mesh. Smooth crimped edges with no staple or string = PP-sealed paper. Plastic stretches; paper tears. The words you want together: “plastic-free” and “certified home compostable”. Or skip the decoding entirely — loose leaf and a steel strainer ball, which is what I did. Full brand-by-brand Australian rundown in the post.