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Glass & ceramicsNot a plastic

Is Glass plastic?

The short answer

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.

Also called: borosilicate glass, soda lime glass, pyrex, is glass better than plastic

How it behaves

The four conditions that decide whether a material is a problem in practice rather than in principle.

Heat
None

Does normal domestic heat degrade it?

Abrasion
None

Do scratching, cutting or flexing generate particles?

Fatty food
None

Does fat pull additives or particles out of it?

Acidic food
None

Do acidic contents attack the surface?

Evidence grade AGrade A — direct measurement

What Glass actually is

Fused silica with additives — soda-lime for jars and bottles, borosilicate where thermal shock resistance matters, as in ovenware. It is chemically inert against fat, acid and heat, and its surface does not degrade into a shedding layer with age, which is the property that separates it from every plastic here.

Where you find it

Bottles and jarsFood-storage containersBakewareDrinkwareBaby bottles

Why Glass is not a microplastic source

Nothing from the glass. The honest detail most sites skip: the format-comparison study measured about 50 particles per litre in glass-bottled water, against 14 for single-use PET and 118 for returnable PET, and attributed the glass result to the closure and the bottling line. Glass is dramatically better and it is not zero, and the residual is in the lid.

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

This is what we recommend switching to

Glass is the alternative named on 17 other material pages — Polypropylene, Polyethylene, HDPE, LDPE, PET. There is no upgrade from here.

Products we've scored involving Glass

Each with its own 0–100 exposure score, evidence grade and sources.

25

Glass electric kettle

Borosilicate glass body with a plastic lid, spout filter and base seals

Moderate

Grade C · 58%

20

San Pellegrino (glass bottle)

Glass with a metal crown cap or a plastic-lined screw cap

Low

Grade A · 86%

17

Pyrex glass storage container

Glass body with a polypropylene lid

Low

Grade C · 60%

16

Baby food in a glass jar

Glass jar with a metal lid and a polymer sealing compound

Low

Grade B · 68%

15

Glass baby bottle

Borosilicate glass with a silicone teat

Low

Grade B · 70%

15

Mountain Valley Spring Water (glass)

Glass with a plastic-lined cap

Low

Grade B · 68%

11

Glass water bottle with a silicone sleeve

Borosilicate or soda-lime glass, silicone sleeve on the outside, steel or bamboo cap

Low

Grade B · 66%

Packaging formats made of it

Glass bottle or jar

The cleanest widely available format. No polymer touches the contents at all except the cap liner, which is a tiny sealing surface. If a product is sold in both glass and plastic, the glass version is the answer.

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 of

Sources

  1. Schymanski 2018 — Compared formats head to head: single-use PET averaged 14 particles/L, returnable PET 118/L, glass bottles 50/L and beverage cartons 11/L.

    Limitation: The glass result is the one people skip. Glass was not zero — particles came from the cap and the filling line, not the bottle wall. Small sample per format.

  2. Mason 2018 — 93% of 259 bottles across 11 international brands contained microplastic; an average of 325 particles per litre across all size classes.

    Limitation: Nile-red staining and optical microscopy only reliably resolve particles above ~100 μm, so its counts are a floor, not a total. Lower numbers here do not mean less plastic than the 2024 study — they mean a less sensitive method.

  3. Sobhani 2020 — Simply tearing, cutting or twisting open plastic packaging generates microplastics at the opening — 10–30 nanograms per 300 cm of tear.

    Limitation: Mass, not particle count, and it does not follow whether those particles land in the food. It is the reason cap and seal design belongs in an exposure score at all.

Frequently Asked Questions

Is Glass a plastic?

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.

Is Glass free of microplastics?

Nothing from the glass. The honest detail most sites skip: the format-comparison study measured about 50 particles per litre in glass-bottled water, against 14 for single-use PET and 118 for returnable PET, and attributed the glass result to the closure and the bottling line. Glass is dramatically better and it is not zero, and the residual is in the lid.

What should I use instead of Glass?

Glass is already one of the materials we point people toward, so there is nothing to upgrade to. Check the components around it instead — lids, seals and liners are usually where the polymer is.

How do I know if something is made of Glass?

Weight, and the temperature — glass feels cold, plastic feels neutral. Borosilicate is marked as such on ovenware and takes thermal shock. Check the lid: a glass container with a plastic lid is glass plus a lid.

Related materials

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.

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