Spoiler: if your bristles are made from nylon, the answer is probably yes. Even if your toothbrush is bamboo.

Every morning and night, you put a toothbrush in your mouth for two minutes. It's one of the most routine things you do. But new research is raising a question that's hard to ignore: are toothbrush bristles releasing microplastics directly into your body every single time you brush?

The short answer, based on current science: for most toothbrushes on the market, yes. And the detail that makes it worse? It doesn't matter whether the handle is plastic or bamboo. The bristles are usually the same material either way.

Here's everything you need to know, including what BRiN does differently and why.

Quick Answer Most toothbrush bristles are made from petroleum-based nylon, which sheds microplastic particles during brushing. Studies estimate 30 to 120 particles per session. Bamboo toothbrushes use the same nylon bristles. Plant-based alternatives like castor oil-derived nylon reduce petrochemical input, though research on their shedding profile is still ongoing.

 

What Are Microplastics, and Why Should You Care?

Microplastics are plastic fragments smaller than 5mm, often microscopic. They come from the breakdown of larger plastic products, synthetic fibres, packaging, and yes, personal care products.

They're everywhere. In oceans, soil, air, drinking water, and increasingly inside us. A landmark 2024 study published in the New England Journal of Medicine found microplastics embedded in arterial plaque in 58% of patients. Those patients were 4.5 times more likely to suffer a heart attack, stroke, or death.

That's the context. Now let's talk about your toothbrush.

Do Toothbrush Bristles Actually Release Microplastics?

According to a 2025 study published in Microchemical Journal, conventional toothbrush bristles do release microplastic particles under normal brushing conditions. Estimates range from 30 to 120 particles per brushing session, depending on the brand, bristle type, and how hard you brush.

That adds up to roughly 2.3 million microplastic particles per year from one toothbrush.

The culprit is nylon, specifically petroleum-derived polyamide (PA6 or PA6.12), which is the standard bristle material across the vast majority of toothbrushes on the market. Friction from brushing causes microscopic fibres and fragments to break off. Most are swallowed. Some may be absorbed.

To be clear: researchers are still working out exactly how much makes it into the bloodstream and what the long-term health effects are. But the directional evidence is not nothing.

Wait, Don't Bamboo Toothbrushes Solve This?

No. And this is one of the most widespread misconceptions in eco consumer products right now.

The bamboo handle is real. But the bristles on virtually every bamboo toothbrush on the market are still made from petroleum-based nylon. Same material. Same shedding profile. Same microplastic concern.

We went deep on this when deciding what BRiN would be. It's actually one of the core reasons we didn't build a bamboo toothbrush. (The full breakdown is in Why We Decided Not To Sell Bamboo Toothbrushes.) A greener-looking handle doesn't change what's going in your mouth.

Should You Actually Be Worried? What the Science Says

Honest answer: the science is real, but the full picture isn't settled yet.

What we know:

•       Petroleum-based nylon bristles do shed microplastic particles during brushing

•       Microplastics are accumulating in human bodies: blood, lungs, placentas

•       High microplastic load in arterial plaque correlates with worse cardiovascular outcomes

What we don't know yet:

•       The exact dose absorbed from toothbrushing specifically

•       Whether bristle-derived microplastics behave differently from other sources

•       Long-term health effects of chronic low-dose oral microplastic exposure

Our take: we don't think you need to panic. But we do think the material choice matters, and that waiting for perfect certainty before making better decisions is not a strategy we're comfortable with.

Why BRiN Uses Castor Oil Bristles Instead of Nylon

When designing BRiN, we chose bristles derived from castor oil, a plant-based source, specifically because of concerns about petroleum-based nylon.

Here's what that means in practice:

•       No petroleum input. Castor oil bristles are made from a renewable, plant-derived feedstock, not fossil fuels. The resulting polymer (nylon 1010 or PA1010) has a significantly lower carbon footprint than conventional nylon.

•       No petrochemical residue. Conventional nylon can carry residual chemicals from petroleum processing. Castor oil-derived nylon doesn't.

•       Same cleaning performance. Nylon 1010 performs on par with conventional nylon for stiffness, flexibility, and durability. Your teeth get the same clean.

You can see exactly what goes into BRiN's brush head refills on the product page. We don't hide the material specs.

We'll be straight with you: there is not yet published research specifically measuring microplastic shedding from castor oil-derived bristles vs. petroleum nylon. That study needs to exist, and we'll be watching for it. What we can say is that the material is fundamentally different: plant-derived, not petroleum-derived, and that difference matters.

We'd rather make the better material choice now, be transparent about what we don't know yet, and update you as the science develops. You can read more about how this fits into our broader material commitments on our Climate Commitment page.

The Bigger Picture: It's Not Just the Bristles

While bristles are the microplastic concern in your mouth, the handle is the plastic concern for the planet.

BRiN handles are made from ocean-bound plastic, material intercepted before it reaches the sea. So every time you use BRiN, you're keeping plastic out of the ocean rather than adding new plastic to the world. We covered the full impact of this in Making Waves with Reusable Toothbrushes.

The handle is also replaceable. When your bristles wear out, only the head goes. Not a whole toothbrush. Not a perfectly good chunk of plastic.

TL;DR

Most toothbrushes, including bamboo ones, use petroleum-based nylon bristles that shed microplastics when you brush. The research is early but it's real, and the direction isn't great.

BRiN uses castor oil-derived bristles as a plant-based alternative: no petroleum input, no petrochemical residue, same clean. We're transparent about what research still needs to be done. But we're not waiting around to make the better choice.

Do toothbrush bristles release microplastics?

Yes, according to current research. Petroleum-based nylon bristles, used in the vast majority of toothbrushes, shed microplastic particles during brushing. Estimates range from 30 to 120 particles per session.

Are bamboo toothbrush bristles free from microplastics?

No. Despite the eco-friendly handle, virtually all bamboo toothbrushes on the market use conventional petroleum-based nylon bristles, the same material as standard plastic toothbrushes. The microplastic shedding profile is essentially the same.

What are castor oil toothbrush bristles?

Castor oil bristles are made from a plant-derived polymer (typically nylon 1010 or PA1010) extracted from castor beans rather than petroleum. They perform identically to conventional nylon but without the fossil fuel input or petrochemical residue. They represent a meaningful material upgrade, though specific microplastic shedding research is still ongoing.

Is there a truly microplastic-free toothbrush?

Not definitively proven yet. Natural bristle alternatives like boar hair exist but have hygiene drawbacks and aren't widely used. Plant-based nylon like castor oil-derived PA1010 reduces petrochemical inputs significantly, but published research on their specific shedding profile is still limited. It's the most credible option currently available, but we're not claiming perfection we can't prove.

How do microplastics from toothbrushes affect your health?

Research is ongoing, but microplastics have been detected in human blood, lungs, and placentas. A 2024 NEJM study found that patients with microplastics in arterial plaque were 4.5 times more likely to suffer cardiovascular events. Whether toothbrush-specific microplastics contribute meaningfully to this load isn't yet established, but reducing exposure from any source is a reasonable precaution.