Is Silicone Plastic? Silicone Vs Plastic Safety & Toxicity

First off, silicone isn’t a singular material. There are different types of silicone suited to different uses, so think of it more as a category. All types of silicones are synthetic polymers though which means they’re man-made. You won’t find any silicone in your backyard that’s for sure.

You might have heard that silicone is related to sand and that’s because silicone contains silicon, a natural element found in sand and rock that’s bonded to oxygen. Greenwashing alert: although silicone does contain silicon it has to go through an intensive process to do this, so any claims of it being a ‘natural’ material are false.

In scientific terms, silicone is made up of a silicon-oxygen backbone with hydrogen and/or hydrocarbon groups linked to the silicon atoms as “sidechains.” Clear as your high school chemistry class?

Despite its dubious origins, silicone has some pretty unique qualities. It’s durable and easy to manufacture. It’s also heat resistant and stable in reaction to chemicals.

These qualities make it a super versatile material that’s used in all sorts of industries from construction and medicine to electronics and homewares At home, you’ll find it in various kitchen items including non-stick bakeware, kitchen utensils, oven gloves, pot holders, food storage, baby bottles, bibs, spoons, hair products, cosmetics, skincare, menstrual cups, children’s toys, and even mouthguards and retainers.

Because it can be used to make malleable, rubbery products it’s sometimes also referred to as a ‘synthetic rubber’. So it silcone rubber, plastic, or neither?

First things first: is silicone a plastic?

Yes. Sort of. Silicone could be considered a type of plastic, in that it’s a synthetic polymer like plastic, but its chemical composition is different. All told, silicone is more of a hybrid that sits somewhere between plastic and synthetic rubber, but its unique qualities set it apart from both of these materials.

Advantages of silicone over plastic:

• Silicone is extremely durable and will last for a long time, much longer than plastic.
• Unlike plastic, silicone is stable when heated (up to a certain temperature).
• Depending on the type of silicone and how it’s made, silicone can be non-toxic and free of harmful chemicals.

Disadvantages of silicone over plastic:

• Silicone is more difficult to recycle than plastic.
• It can still contain toxic ingredients and its safety for food contact materials, cookware and cosmetics is questionable (more on this below).

One way that silicone – at least food grade silicone – is different from some traditional plastics is that it doesn’t contain any estrogen mimicking BPA. So, it silicone safer than plastic?

Well, the stability of silicone means that it doesn’t degrade when frozen or heated making it a safer option than plastic, hence it being the foundation in many kitchen tools. And because silicone isn’t biodegradable, it’s not going to break down and release microplastic into the environment in the same way as plastic. It also doesn’t release toxic fumes when it’s burned, unlike plastic.

However, to really understand the safety of silicone we need to dig a little deeper and review the evidence on silicone toxicity.

Researchers have found that many consumer products contain cyclic and linear siloxanes (silicone-based compounds) that us humans are exposed to daily including via indoor air. As for whether exposure to these siloxanes is problematic, the jury is still out.

The variation in chemical groups, particle sizes and molecular weight affect the safety of silicone products and silicone can also contain additives and fillers depending on how it’s been manufactured.

Low molecular siloxanes including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) are often found in skincare, hair products and cosmetics. It is these smaller molecules that have raised concern in relation to both human health and the environment.

But even so, opinion appears divided. For example, while Health Canada’s assessment of Siloxane D5 found that it isn’t a concern for human health or the environment, the European Chemicals Agency has decided that the use of D4, D5, and D6 should be restricted for certain products.

Beyond siloxanes, we have to consider that not all silicone is created equally, and there are different grades depending on the intended use of a product.

Low quality silicone used for bakeware and other products can also contain plastic fillers and additives which negate the benefits of pure silicone. Far from non-toxic bakeware—and oftentimes, not even very heat resistant. The two highest quality grades of silicone are:

• Food Grade Silicone: During the production of silicone polymers, there’s a purification stage that removes the low molecular weight siloxanes . Food-grade silicone has been ‘platinum cured’. In other words, using this method the silicone is purified to the extent that it is deemed safe for use in direct contact with food.
• Medical Grade Silicone: The gold standard of silicone, medical grade silicone is manufactured to an even higher degree of purity. It doesn’t contain toxins, is hypoallergenic and has been tested and approved by the FDA for biocompatibility, hence its widespread use in cosmetic and surgical implants (i.e. breast implants) as well as bandages, dressings, and contact lenses.

Is Silicone Safe For Cooking?

Yes and no. Chemical migration from food contact materials is a hot (pot) topic, and by now, we’re well aware of this in the case of plastic, but silicone is less clear.

A few years ago, the Food Packaging Forum produced a comprehensive dossier reviewing the chemical migration and toxicology of silicones. Whilst several studies highlighted in the dossier detected chemical migration below the upper safety limits, one study by the Swiss Federal Office of Public Health found that although stable at temperatures up to 150C, heating above 200C caused a significantly higher migration of volatile compounds.

A more recent study that looked at off-gassing and chemical migration into food from newly purchased silicone baking molds also raised some concerns. The authors of the paper concluded that molds should only be used after precleaning and following the strict temperature guidelines recommended by the manufacturers.

Remember, not all silicone is food safe. It’s super important to make sure that the silicon you buy is food grade. Regular silicone for industrial use isn’t food safe and lower-quality silicone may contain fillers and additives that would be toxic if it came into contact with your food.

Additionally, pure silicone is oven safe and dishwasher safe. In other words, it won’t melt when exposed to even high temperatures up to 400° F to 450° F (play it safe and assume the lower). However, if that silicone has been blended with other plastics, those plastics will melt at those temperatures.

This is really common with silicone alternatives to Ziploc bags, that use plastic components in, say, the zipper seal. Put these in the dishwasher and suddenly you have a useless warped bag that doesn’t seal (ask us how we know).

In addition to buying from a brand you trust, there’s a simple check you can do at home to find out if a product is made from food grade silicone. Pull, pinch or twist the surface of the item and if you see any white showing through, then the product contains a filler and shouldn’t be used for food.

Even so, we actually recommend handwashing whenever possible, especially where baby items are concerned, as it’s more gentle and gives you a chance to check the item over.

Here are our top tips for using silicone safely, whether we’re talking plastic-free food storage or your menstrual cup:

• Keep it cool. Avoid silicone cookware if you can (opt for glass, ceramic and stainless steel instead). Silicone cooking utensils (llike spatulas) are typically fine as they don’t really stay in contact with hot surfaces long enough to be a problem and they’re certainly safer than plastic alternatives. The occasional boiling of a menstrual cup to disinfect is fine, but don’t let the water get too hot or let it sit too long.
• Check the label. Make sure you are using a good quality food grade silicone from a reputable brand.
• Use the sink. Hand wash silicone items to be sure you’re not degrading them in the dishwasher.

End-Of-Life: Is Silicone Recylable?

Firstly, silicone isn’t biodegradable. It takes hundreds of years to decompose, meaning there’s potential for accumulating large amounts of silicone waste if it can’t be recycled.

Although it can be, it is very difficult to recycle and can only be done at specialized recycling facilities where it’s often downcycled into a different product. If you don’t have one nearby (as is likely), Terracycle offers some free mail-in programs for specific brands of silicone products, or you can purchase a Zero Waste Box and put any other silicone items in there.

Also, industrial waste composed of just silicone is easier to recycle than consumer waste where silicone is attached to other materials. Yet another reason to buy pure, high-grade silicone materials only.