Are Toothbrush Bristles Plastic? The Truth About Bamboo, Nylon and Castor Oil

March 24, 2026 Tracey Bailey

Lately, we’ve been getting a lot of questions about toothbrushes — especially the bristles.

People are trying to reduce their exposure to microplastics and avoid plastic where they can. And then they pick up a bamboo toothbrush… and realise the bristles are still plastic.

That’s where the confusion starts.

Are “castor oil bristles” actually plastic-free?
And is there such a thing as a truly plastic-free toothbrush?

Let’s break it down properly.

What toothbrush bristles are actually made from

Most toothbrush bristles — including eco and bamboo toothbrushes — are made from polyamide.

Polyamide is the scientific name for a group of materials commonly known as nylon.

So when you see:

“nylon bristles”
“polyamide bristles”
“castor oil bristles”

👉 They are all variations of the same material family: engineered plastic polymers designed for strength, flexibility and hygiene

The main types used in toothbrushes

→ Nylon-6, Nylon-6,6

Petroleum-derived polyamides (traditional toothbrush bristles)

→ PBT (polybutylene terephthalate)

Another synthetic polymer used for durability and moisture resistance

→ Nylon-11 (PA11)

A polyamide derived from castor oil (plant-based source)

What’s important to understand

Even when derived from plants:

👉 They are still synthetic polymers (plastics)

The difference is the source of the carbon, not the nature of the material.

Are “castor oil bristles” plastic-free?

No.

They are plant-based plastic, not natural fibres.

They are made by:
Castor beans → castor oil → chemical converted with petrochemical inputs → polyamide (nylon-11)

✔ What this improves

Reduces reliance on fossil fuels
Uses a renewable plant source

❗ What it doesn’t change

Still a plastic material
Not compostable
Not microplastic-free

Do toothbrush bristles release microplastics?

Yes — this is now well established.

Studies have found:

30–120 particles released per brushing session
Many particles are extremely small — including sizes that are not yet fully understood in terms of health impact

This applies to:

Nylon-6 / Nylon-6,6
PBT
Nylon-11 (castor oil-based)

👉 Plant-based plastic behaves the same as petroleum-based plastic in use

Should you be concerned?

Here’s the balanced view based on current research.

What we know

Microplastics are released during brushing
Exposure in the mouth occurs
Some particles are extremely small

What we don’t yet know

How much is absorbed into the body
The long-term health impact from toothbrush use specifically

Context matters

Toothbrushes are just one source of microplastics, alongside:

Food packaging, storage, heating
Bottled water and plastic drink bottles
Synthetic textiles

Are there plastic-free toothbrush bristles?

Not without trade-offs.

Boar hair (animal bristles)

✔ Plastic-free
✔ Biodegradable

But:
❌ Not vegan
❌ Can harbour bacteria
❌ Less consistent performance

Plant fibre bristles (emerging)

✔ Plastic-free
✔ Compostable

But:
❌ Not widely available
❌ Break down very quickly
❌ Inconsistent performance

Why plant fibre bristles haven’t replaced nylon

Various plant-based options have been explored — but none yet meet the performance needed for everyday brushing.

🌿 Sisal (agave fibre)

Too stiff
Can damage gums & enamel

🌿 Miswak sticks

Traditional use, requires technique
Inconsistent cleaning

🌿 Cellulose / plant fibres

Too stiff or too soft
Poor cleaning, gum irritation

🌿 PLA bioplastic (corn-based)

Wears out 5-7 days!
Not viable for real use

Polyamide (nylon) bristles

✔ Hygienic
✔ Durable
✔ Reliable cleaning performance

But:
❌ Plastic
❌ Can shed microplastics

The honest comparison: there is no perfect toothbrush


Material	Microplastics	Chemical exposure	Hygiene	Performance	Compostable
Castor oil nylon	✔ Yes	Low	✔ High	✔ Excellent	❌ No
Petroleum nylon	✔ Yes	Low–moderate	✔ High	✔ Excellent	❌ No
Boar hair	❌ No	Very low	❌ Lower	❌ Moderate	✔ Yes
Plant fibre (new)	❌ Minimal	Very low	❓ Unknown	❌ Poor	✔ Potential

What we offer at Biome

We offer both:

Castor oil-based polyamide bristles (Brush with Bamboo)

Bamboo toothbrushes with conventional Nylon 6 and PBT bristles (Biome, Dr Hishams, Environmental Toothbrush ranges)

Why both? Because each option meets different priorities:

Castor oil bristles → lower fossil fuel impact
Nylon/PBT bristles → proven durability and performance

But we are clear about one thing:

👉 All of these are plastic-based materials
👉 None are completely microplastic-free

The question we hear most

“Do you sell a toothbrush with completely plastic-free bristles?”

At this stage, no, because:

we don’t offer animal bristles
current plant fibre options don't meet hygiene and durability standards

What you can do instead

If your goal is to reduce plastic exposure, here are the steps likely to make the biggest difference:

Replace your toothbrush regularly. This is one of the most important things you can do, because worn bristles are more likely to shed tiny particles.
Choose plant-based bristles where possible. Castor oil-based bristles are still a form of plastic, but they reduce reliance on fossil fuels compared with petroleum-based bristles.
Focus on the bigger sources too. Toothbrushes are only one part of the picture. You can often reduce far more plastic exposure by cutting back on:
- processed food packaged in plastic
- food stored or heated in plastic
- synthetic clothing
- bottled water or drinking from a plastic water bottle

Tracey's thoughts

It’s not realistic to eliminate all plastics from our lives — and trying to do so can create unnecessary stress.

But we can make improvements across the everyday items we use, and that can have a meaningful impact over time.

Castor oil toothbrush bristles are a better option — but not a perfect one.

They reduce reliance on fossil fuels and may contain fewer petrochemical inputs, but they don’t eliminate microplastics. Conventional nylon and PBT bristles still offer proven performance and durability.

But, whichever bristle you choose, it's important to:

✔ choose a bamboo handle to save the waste of plastic handles
✔ look for bristles that are pressed in, not glued in
✔ replace your toothbrush regularly

It’s also worth being aware: as demand grows, more brands are starting to use the term “castor oil bristles”, but not all are independently certified or transparent about what they contain or where they are made.

At Biome, we support Brush with Bamboo because the bristles are made in the European Union and are USDA Certified 100% Biobased Bristles.