What it is
Polyethylene terephthalate is a polyester — long chains built from ethylene glycol and terephthalic acid. It’s the glassy-clear, lightweight plastic of drink bottles: look for the “1” in the recycling triangle. Spun into fibre, the identical polymer is sold as polyester clothing; melted into bottles, it’s PET. Same molecule, different outfit.
Where you meet it
Water and soft-drink bottles, juice bottles, condiment and peanut-butter jars, berry punnets, deli trays, some “silken” pyramid teabags — and most of your activewear.
What the research shows
The headline number comes from Columbia University: an average of roughly 240,000 plastic particles per litre of bottled water, about 90% of them nanoplastics small enough to cross into tissues — 10 to 100 times higher than earlier estimates (PNAS, 2024, Columbia’s summary) lab. The under-reported detail: the most abundant polymer they identified wasn’t PET but polyamide (nylon) — likely shed by the purification filters — and only ~10% of all detected particles matched the seven plastics they searched for. The bottle wall is one source among several; bottled water is a system that sheds.
PET is also one of the polymers most often found in people. In the first study to measure plastic in human blood, 17 of 22 healthy donors carried quantifiable plastic (mean 1.6 µg/mL), with PET among the most common polymers (Vrije Universiteit Amsterdam, Environment International, 2022) human obs. — presence, not proof of harm.
Two more PET-specific findings: “silken” PET/nylon teabags shed billions of particles per cup at brewing temperature (McGill, ES&T, 2019) lab, and antimony — the catalyst used to make PET — migrates into the drink in increasing amounts with heat and storage time (ES&T, 2006) lab, though measured beverage levels generally sit below regulatory limits agency.
What I do
Bottled water was the first habit I dropped — filtered tap water into glass or stainless steel replaces the product with a quarter of a million particles per litre. I don’t leave PET bottles cooking in the car, don’t refill them with anything warm, and my tea is loose-leaf.
The honest bit
Despite the scary-sounding “terephthalate”, PET contains none of the phthalate plasticisers people worry about, and no BPA — cold and single-use, it’s one of the more inert commodity plastics. The problem isn’t exotic chemistry; it’s that we buy our most-consumed liquid wrapped in a material that sheds, then wonder why it’s in our blood.