Is Silicone Really Plastic Free? And Other Greenwashing Myths

A lot of brands are labelling silicone "plastic free". Here's what that claim is actually leaving out.

There's an explosion of silicone kitchenwares like baking mats, food storage bags, baby feeding sets and air fryer liners, many labelled as "plastic free".

It's an easy claim to make, and an easy one to believe when we are all keen to avoid plastic chemicals and waste.

But is it actually plastic free? The honest answer is: it depends on what you mean by "plastic".

At Biome, we think this is one of the clearer examples of greenwashing in the sustainable living space at the moment. Not because silicone is necessarily a bad material but because "plastic free" is being used in a way that doesn't hold up to scrutiny.

So, is silicone plastic?

Most plastics are built on a carbon-based backbone, made from petroleum or natural gas. Silicone is different: its backbone is a chain of silicon and oxygen atoms (derived from silica, or sand), with carbon-based groups attached to it. That's a genuinely different chemical structure, and it's the reason silicone behaves differently under heat – it doesn't melt or warp the way conventional plastic does.

Where the "plastic free" claim runs into trouble is the rest of the picture:

• Silicone is still a synthetic, manufactured polymer, not a naturally occurring material.
• Making it requires fossil-fuel-derived carbon and hydrogen alongside the silica.
• It behaves like plastic in the ways that matter for end-of-life: it doesn't biodegrade, and it's not accepted in most household recycling.

So silicone sits in a genuine grey area. It isn't a conventional petroleum plastic, but calling it "plastic free" gives the impression it's closer to a natural material like wood, wool or cotton than it actually is. That's the greenwashing problem in a nutshell – the claim is technically defensible in a narrow chemistry sense, while implying something broader that isn't quite true.

"Silicone is natural because it's made from sand"

This is another claim we see a lot, and it follows the same pattern: true as far as it goes, misleading in what it implies.

Silica (sand) is indeed the starting point for silicone, and it's a naturally occurring, abundant material. But that's also where the "natural" story stops.

To turn sand into silicone, the silica goes through an intense industrial process that extracts silicon, then combines it with carbon and hydrogen (typically sourced from fossil fuels) under very high heat, using various chemical catalysts, to build the synthetic silicone polymer. What comes out the other end is a man-made material that doesn't exist in nature and can't be found anywhere in the environment without a factory involved.

By that same logic, glass would be "natural because it's made from sand", and even conventional plastic would be "natural because it's made from crude oil" – oil being a naturally occurring substance too.

Almost every synthetic material starts from something dug out of the ground. What actually determines whether a finished product is "natural" is how much processing and synthetic chemistry stands between the raw material and what ends up in your kitchen, not simply what its ingredients trace back to.

Silicone is more accurately described as a synthetic material derived from sand and petrochemicals. It's a fair and useful distinction from petroleum-based plastic, but it doesn't put silicone in the same category as genuinely natural materials like beeswax, cotton, wool or wood.

How silicone is made 

Metallurgical gravel or quartz is the primary raw material for making silicone.  You don't need much imagination to work out the intensive processing required to get solid quartz from its rock state to a brightly coloured squishy baking cup!

Is silicone sustainable?

This is where nuance matters, because the honest answer is "more sustainable than some plastics, in some ways" – not an unqualified yes.

Where silicone does reasonably well:

• It's extremely durable. A good silicone product can last many years, which matters when you're comparing it to single-use plastic.
• It withstands high and low temperatures without degrading the way many plastics do, so it doesn't need replacing as often.
• Made well, it's a genuine upgrade over disposable cling wrap, snap-lock bags or single-use plastic liners.

Where it falls short of "sustainable":

• It's not biodegradable. Left in the environment, silicone can persist for decades, by some estimates far longer.
• It's not readily recyclable. Standard council recycling won't take it, and the specialist facilities that can process it are limited and not widely accessible.
• Manufacturing silicone is energy intensive, and by some measures produces more emissions per kilogram than common plastics like PET, though this is offset over time by how long a silicone product lasts if it's genuinely reused for years.

Our view is that silicone can be a reasonable choice when it's replacing something single-use and you'll get years of genuine reuse out of it. It's a much harder case to make for "sustainable" when it's marketed as a wholesale alternative to natural materials, or when it's being repeatedly bought and discarded like the very plastic it's meant to replace.

Is silicone safe?

Food-grade, platinum-cured silicone has a reasonable safety profile for many everyday uses. It's generally free of BPA and phthalates, which is a genuine point in its favour compared with many conventional plastics, and it's widely considered inert and stable under normal, low-heat use.

Where the picture gets less clear is at high heat, and with lower-quality silicone.

• Quality varies enormously, and there's no consistent certification scheme that lets a consumer verify what grade of silicone they're actually buying. Cheaper silicone can be bulked out with plastic fillers, which changes how it behaves and what it might release.
• Research on high-heat use is still developing. Some studies have found that silicone cookware can release compounds called siloxanes when exposed to high heat or fatty foods, and one study testing a batch of silicone kitchenware and bakeware found a notable proportion showed some hormone-disrupting activity in cell testing. This research is still emerging, sample sizes are often small, and results vary by product and manufacturer – but it's enough that we don't think "silicone is inert" is a settled fact for high-heat cooking.

This is exactly why Biome's recommendation is not to use silicone for high-heat baking or air fryer cooking. There's no conclusive research on what silicone releases when it's repeatedly exposed to high temperatures, and there's no certification scheme that lets you verify the quality of the silicone in a specific product. Until both of those exist, we think glass, ceramic and stainless steel are simply the safer bet for anything going into an oven or air fryer.

For cooler, lower-risk uses, such as food storage or freezer bags, the safety profile looks considerably better.

Is silicone a good swap if I'm trying to avoid plastic chemicals?

This question comes up a lot at the moment – especially from people after watching The Plastic Detox documentary – and often from people who've just done a clear-out of plastic food storage at home and are looking for what to replace it with.

It's a reasonable instinct, and silicone does solve part of the problem. Genuine food-grade silicone is free of BPA and phthalates, the two chemical families most associated with plastic exposure concerns – hormone disruption, fertility impacts, and so on. If your main goal is avoiding those two specific compound groups, swapping a plastic container for a silicone one is a legitimate step forward.

But it's worth being clear that this isn't a swap to "chemical free". Silicone comes with its own class of compounds of concern, called siloxanes, which have been shown to migrate out of silicone products, particularly under heat and in contact with fatty foods. Some of these siloxanes are flagged by European chemical regulators as substances of very high concern, and lab studies on batches of silicone kitchenware have found a meaningful proportion contain detectable heavy metals or show hormone-disrupting activity in cell testing.

So the risk doesn't disappear with silicone, it changes shape. And critically, it isn't a flat risk across all uses:

• Cold storage – fridge or freezer is a considerably lower-risk scenario. This is where silicone bags and containers make the most sense as a swap away from plastic wrap or snap-lock bags.
• Repeated high-heat use – oven, air fryer, direct heat cooking is where the concerns around siloxane migration and chemical release are strongest, since heat and fat content are the two factors research consistently points to.

That's really the heart of Biome's position: silicone isn't inherently unsafe, but it also isn't the clean alternative some marketing suggests. If you're motivated to reduce chemical exposure in the kitchen, silicone food storage bags for cold use are a genuinely reasonable choice. For anything going into the oven or the air fryer, we'd still point you towards glass, ceramic or stainless steel – materials with a much longer track record, and none of the open questions silicone still carries at high heat.

Will silicone give off microplastics?

Not in the same way conventional plastic does, but "no" isn't quite the full answer either.

Silicone doesn't fragment into the classic microplastic particles associated with things like synthetic fabric or degrading plastic packaging. Under normal, gentle use, it's genuinely more stable than most plastics.

However, research using advanced imaging techniques has found that silicone products – including kitchen sealants, bakeware and baby items like pacifiers – can shed microscopic and even smaller nanoscale particles, particularly when subjected to heat, mechanical stress, abrasive cleaning, or ageing. These particles are chemically different from petroleum-based microplastics, and current evidence suggests they may not persist in the environment for as long. But "chemically different" isn't the same as "risk free", and the toxicity of these silicone particles hasn't been well studied yet.

The practical takeaway: silicone is a lower-shedding material than conventional plastic, but "doesn't shed microplastics" is an overstatement of where the current research actually sits.

Is silicone less toxic than plastic?

In many everyday comparisons, yes – food-grade silicone generally comes out ahead of low-grade or unknown plastics, particularly around BPA and phthalates, which are well-documented concerns in some conventional plastics.

But "less toxic than plastic" is a comparison, not a clean bill of health. It depends heavily on:

• the grade of silicone – platinum-cured, food-grade silicone behaves very differently to cheap, filler-heavy silicone
• the use case – cold storage carries a different risk profile to repeated high-heat cooking
• what it's being compared to – silicone looking better than a low-grade plastic doesn't automatically make it as safe as glass, ceramic or stainless steel.

Why avoid silicone (in some situations)?

We wouldn't say avoid silicone altogether – for the right use, it's a genuine improvement on single-use plastic. But there are specific situations where we think it's worth choosing something else:

• High-heat cooking and baking, including air fryers – see above.
• When you can't verify the grade, such as very cheap, unbranded silicone products with no clear certification or country-of-origin information.
• When a more time-tested material does the same job just as well – glass and stainless steel have generations of use behind them, with none of the open questions silicone still carries.
• If you're specifically trying to avoid petroleum-derived products, since silicone still relies on fossil-fuel-derived carbon and hydrogen in its manufacture, even though its backbone differs from conventional plastic.

Is 100% silicone toxic to humans?

Genuine, high-grade, platinum-cured food silicone is generally considered safe for everyday use, and is accepted as safe by food safety regulators in many countries when used within its intended temperature range. It isn't accurate to call it broadly toxic to humans.

That said, "100% silicone" on a label doesn't tell you the grade, the curing process, or whether the manufacturer has tested it at the temperatures you'll actually be using it at. That's the gap we keep coming back to: the material itself has a reasonable safety profile in principle, but the lack of a consistent certification scheme means a consumer often can't verify what they're actually getting, especially for high-heat use.

Safer uses of silicone (and where we'd steer clear)

Given everything above, it's worth being concrete about which silicone uses we're comfortable with and which we're more cautious about. Here's how we think about it across the kind of silicone products in the Biome range.

A simple rule of thumb: if a silicone product is doing its job at body, room or fridge temperature, we're comfortable with it – with the proviso that it is food grade platinum-cured silicone. Once it's going into a hot oven, air fryer, or sitting directly on a heat source for an extended time, we'd reach for glass, ceramic or stainless steel instead.

Our take

Silicone isn't the villain some headlines make it out to be, and it isn't the plastic-free hero the marketing suggests either. It's a genuinely different material to conventional plastic, with real advantages for the right job – replacing single-use plastic bags, wrap and disposable liners being the clearest example.

Until there's conclusive research on what silicone releases under repeated high-temperature cooking, and a proper certification scheme for silicone quality, our recommendation stays the same: choose glass, ceramic or stainless steel for the oven and the air fryer, and save silicone for the jobs it's genuinely well suited to.

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Frequently asked questions

Is silicone plastic free? Not entirely. Silicone has a different chemical backbone to conventional plastic and isn't a traditional petroleum plastic, but it's still a synthetic polymer that relies on fossil-fuel-derived materials, doesn't biodegrade, and isn't widely recyclable.

Is silicone a good alternative if I'm trying to avoid plastic chemicals? For cold food storage, it can be a reasonable swap, since genuine food-grade silicone is free of BPA and phthalates. For high-heat cooking, it's a different story – silicone can release its own compounds of concern (siloxanes) under heat, so it isn't a swap to "chemical free".

Is silicone sustainable? It can be, when it's genuinely replacing single-use plastic and gets years of reuse. It's not biodegradable or easily recycled, so it's not a sustainable choice if it's being treated as disposable.

Is silicone safe? Food-grade, platinum-cured silicone has a reasonable safety profile for everyday, low-heat use. The evidence is less settled for repeated high-heat cooking, and there's no certification scheme to verify the quality of the silicone in a specific product.

Will silicone give off microplastics? Not in the traditional sense, but research shows it can shed microscopic and nanoscale particles under heat, mechanical stress or ageing. These particles differ chemically from conventional microplastics, but they're not yet well understood.

Is silicone less toxic than plastic? Often, particularly compared with low-grade plastics containing BPA or phthalates. But this depends on the grade of silicone and how it's used, especially at high heat.

Is 100% silicone toxic to humans? Genuine, high-grade food silicone is generally considered safe for its intended use, but "100% silicone" on a label doesn't confirm the grade or how it performs at high heat.