Is Polypropylene plastic?
Reading this off a cosmetics label? This page is about Polypropylene as a material things are made from. For Polypropylene as an ingredient on an INCI list — what it is doing in the formula and whether it counts as a microplastic ingredient — go to the ingredient page.
The short answer
Yes, polypropylene is a plastic — resin code 5, and one of the more thermally stable food plastics. That stability is exactly why it ends up in the containers people microwave, which is where its problems start.
Also called: PP, resin code 5, number 5 plastic, is polypropylene safe
How it behaves
The four conditions that decide whether a material is a problem in practice rather than in principle.
- Heat
- High
Does normal domestic heat degrade it?
- Abrasion
- High
Do scratching, cutting or flexing generate particles?
- Fatty food
- Moderate
Does fat pull additives or particles out of it?
- Acidic food
- Low
Do acidic contents attack the surface?
What Polypropylene actually is
A carbon-chain polymer made from propylene. It resists heat better than PET or polystyrene, tolerates fats reasonably well, and is cheap to mould, which is why it dominates yogurt pots, takeaway tubs, reusable food boxes, bottle caps and infant feeding bottles. Its reputation as "the safe one" is relative to other plastics, not absolute.
Where you find it
What Polypropylene releases, and when
Two directly measured pathways. Heat: three minutes in a microwave released up to 4.22 million microplastic and 2.11 billion nanoplastic particles per square centimetre from PP containers, and polypropylene infant bottles prepared with 70°C water released 1.3–16.2 million particles per litre of formula. Abrasion: chopping on a PP board generated an estimated 14.5–71.9 million particles per person per year. "Microwave safe" is a statement about the container not warping.
Graded A. This exact product, or an item identical to it, has been measured for particle release in a peer-reviewed study. The number is anchored to a laboratory result rather than to a material. How evidence grades work →
How to tell you're holding it
A 5 inside the recycling triangle, often with "PP" underneath
Slightly waxy feel, more flexible than PET, does not crack like polystyrene
Usually opaque or translucent rather than glass-clear
Almost every screw cap on a bottle is polypropylene, whatever the bottle is
Switch to
Glass
No polymer touches the contents, which makes glass the cleanest widely available food material. Worth knowing: glass bottles measured around 50 particles per litre in the one study that compared formats — from the cap and the filling line, not the glass.
Stainless steel
No microplastics at all — steel is a metal and cannot shed a polymer. The catch is the parts around it: a steel bottle is only as clean as its lid, and the lid is almost always plastic.
Ceramic and stoneware
Fired, glazed ceramic sheds no polymer. "Ceramic non-stick" cookware is a different thing — a sol-gel silica coating on metal, which is not PTFE and is also not the same as a stoneware dish.
Products we've scored involving Polypropylene
Each with its own 0–100 exposure score, evidence grade and sources.
Polypropylene baby bottle
Polypropylene (#5) bottle with a silicone teat
Grade A · 90%
Plastic cutting board
Polypropylene or polyethylene board
Grade A · 88%
Tupperware plastic container
Polypropylene or polyethylene tub with a sealing lid
Grade B · 74%
Ziploc plastic container
Polypropylene (#5) tub with a snap-on lid
Grade B · 74%
Yogurt in a plastic pot
Polypropylene or polystyrene pot with a foil lid
Grade C · 60%
Bagged salad
Polypropylene or PET film bag
Grade C · 58%
Protein powder in a plastic tub
HDPE or polypropylene tub with a plastic scoop
Grade D · 46%
Packaging formats made of it
Polypropylene tub
One of the more thermally stable food plastics, which is why it is used for yogurt and microwave containers. Stability is relative though: PP is still a carbon-chain polymer, and it is usually the format people microwave.
Plastic lid or cap
The most overlooked component, and the reason a stainless steel bottle is only as clean as its lid. Threads grind against each other at every open and close, generating particles directly above the contents.
Plastic coffee pod
Pressurised hot water forced through a plastic capsule, which is close to a worst-case combination of heat, pressure and direct contact. Aluminium capsules are meaningfully better because only a thin inner liner touches the water.
Not sure what yours is made of?
Most products never state the polymer, and a resin code on the base only tells you about the body — not the lid, the liner or the seal. Scan the item and the app identifies the materials in it, then scores them together.
Identify what mine is made ofSources
Hussain 2023 (Nebraska) — Three minutes of microwaving released up to 4.22 million microplastic and 2.11 billion nanoplastic particles per square centimetre of container surface.
Limitation: Polypropylene and polyethylene containers with water and acetic acid, not real food. The headline figure is the worst case in the study, per cm², not per meal.
Li 2020 (Nature Food) — Polypropylene infant bottles prepared to WHO sterilisation guidance released 1.3–16.2 million microplastic particles per litre of formula.
Limitation: Release scaled with water temperature — the highest numbers came from the 70°C step WHO recommends for killing bacteria. The study explicitly did not recommend abandoning that step, and no health outcome was measured.
Yadav 2023 — Chopping on a plastic board generated an estimated 14.5–71.9 million polypropylene microplastics per person per year, and around 79.4 million from a polyethylene board.
Limitation: Controlled chopping by a set protocol, extrapolated to annual figures. Real kitchens vary enormously in board use, knife type and replacement frequency.
Du 2020 — Take-out containers released 3–29 microplastic particles each, with polypropylene containers the most common source.
Limitation: Counts particles above the detection limit of the method used, so it says nothing about the nanoplastic fraction, which other work suggests dominates by number.
Frequently Asked Questions
Is Polypropylene a plastic?
Does Polypropylene release microplastics?
What should I use instead of Polypropylene?
How do I know if something is made of Polypropylene?
Related materials
Glass
No polymer touches the contents, which makes glass the cleanest widely available food material. Worth knowing: glass bottles measured around 50 particles per litre in the one study that compared formats — from the cap and the filling line, not the glass.
Stainless steel
No microplastics at all — steel is a metal and cannot shed a polymer. The catch is the parts around it: a steel bottle is only as clean as its lid, and the lid is almost always plastic.
Ceramic and stoneware
Fired, glazed ceramic sheds no polymer. "Ceramic non-stick" cookware is a different thing — a sol-gel silica coating on metal, which is not PTFE and is also not the same as a stoneware dish.
Polyethylene
Yes. Polyethylene is the most-produced plastic on earth and the polymer most often detected in human tissue — it was the plastic found in 58.4% of carotid plaques in the 2024 NEJM study.
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