Ingredient glossary
Depends on contextMicroplastics and nanoplastics
What it is
Microplastics are plastic fragments smaller than 5 millimeters, and nanoplastics are smaller still. In baby feeding, the question is whether a bottle, nipple or cup releases particles into milk or formula, particularly when it is heated, shaken, washed or sterilized.
Why it's flagged
A 2020 Nature Food study measured microplastic release from polypropylene infant bottles as high as 16,200,000 particles per litre, with sterilization and high-temperature water significantly increasing it, and modelled infant intake of 14,600 to 4,550,000 particles per person per day. Our research records a 2025 Food Control study reporting particle release from tested PPSU and silicone feeding bottles, which we could not re-read. Consumer lawsuits have since challenged how bottles were marketed on this point.
How concerned to be
Particles were measured under laboratory or use-simulation conditions, and the health significance of infant ingestion at those levels has not been established. We do not call any bottle microplastic-free, because no exact-product test covering the relevant particle sizes was found for any product we reviewed, and we do not call any bottle toxic on this evidence. Lawsuit allegations are allegations, not test results.
What it's called on a label
Look for any of these on an ingredient list: Plastic particles, Particle shedding, Nanoplastics, Microplastic-free, Particle-free, BPA-free.