Is Silicone Biodegradable? Does It Breakdown?

What comes to mind when you think about the word ‘silicone’? My first thought was cookware; like measuring cups, spatulas, silicone baking mats, and cake moulds galore. Available in a wide array of colours, very durable, and widely regarded as eco-friendly options, it’s easy to forget about what will happen to these silicone alternatives once they are worn through… What’s more, is silicone biodegradable? What is it even made of? It otherwise looks and behaves quite similarly to plastics as far as I can tell. So is silicone a plastic? What makes it so much better, safer, and eco-friendly?

All of these questions far supersede the benefits of a clean worry free bake when we consider the impact these kinds of choices stand to have on our health and on our planet.

If you think so too, read on for everything I found out about silicones and their role in a sustainable lifestyle.

What is silicone? 

If you were wondering if silicone is a plastic? It is, but silicones are actually a family of synthetic polymers of their own. Silicone polymers can come in the form of liquids, gels, rubber, foams, or solids; and are all embraced for being more temperature resistant and more durable than other plastics. They also have a low reactivity to chemicals, are quick-cooling, and stain-resistant. 

Silicone polymers are used in a wide range of applications; from the healthcare and aerospace industries to textiles, construction, and of course, cookware. So things like breast implants, engine gaskets, textile coatings, sealants, and measuring cups, of course, can all be made using these polymers, which are deemed highly effective in all of these industries. 

What is silicone made of? 

Often confused with silicon, silicones contain silicon but they are not the same. Silicon is derived from silica, one of the most common elements on earth. In fact, every time you go to the beach, you are most often first stepping into another kind of ocean; one made mostly of pure crystalline silica. (Institute of Medicine – US, 1999) It is all those tiny rosy- or clear colored gemstones that are used to make silicon and later silicones. Silica is also widely used in other things like concrete, ceramics, and pottery, among other things.

A silicone bag with veggies in it.

How is silicone made? 

The process of making silicones starts with silica. It is heated to temperatures as high as 1800˚C to create what is called isolated silicon. (SIMTEC, 2017) The silicon is then combined with methyl chloride (using heat),  followed by further reactions using other chemicals and more heat. While they are made in large part using a naturally occurring and abundant element, the resulting materials are still synthetic polymers like other plastics. 

Is silicone biodegradable? 

The answer depends on what we define as biodegradable since pretty much anything will naturally degrade over time. So let’s start by defining what counts as truly biodegradable. 

A given item or product is considered biodegradable when it can be broken down by microorganisms (like bacteria, fungi, or microbes) and be reabsorbed by the environment without causing pollution. (BBC Good Food, 2021) An apple core for example, is generally considered biodegradable. 

Relevant regulatory bodies also support this definition. The Canadian Competition Bureau defines biodegradable as “a characteristic of a product or packaging that, with respect to specific conditions, allows it to break down to a specific extent within a given time.” They also specify that claims of degradability “shall not be made for a product or packaging, or component of a product or packaging, that releases substances in concentrations harmful to the environment”. Furthermore, and of great importance, “a claim that a product is biodegradable should be made only if it would be true in the circumstances in which the product is likely to be disposed of”. (Canadian Office of Consumer Affairs, 2012)

In the States, the US Federal Trade Commission specifies that items that do not completely decompose within one year after customary disposal would be deceptively labelled under degradable terms. (EPA, 2020)

So in order to be considered biodegradable an item or product needs to break down by microorganisms within a specific amount of time, without leaving harmful chemicals behind, and be likely to be disposed of in ways that will support its degradation. 

Based on this criteria, silicones are not biodegradable because they are likely to take far more than a year to degrade (once they are worn) and release harmful substances into the environment when they do degrade, like other synthetic polymers do. They are also most likely to wind up in landfills which do not support decomposition since they are designed to keep oxygen and sunlight out which are needed for decomposition. 

How Long Does Silicone Take to biodegrade?

It turns out it is still difficult to say how long it takes for silicones to degrade since biodegradation tests are difficult to perform on silicone polymers because they are so durable on several ends of the spectrum. With low solubility and high vaporization rates, we are currently still left with a big question mark surrounding this question. (Clean Technologies and Environmental Policy, 2008) But if less durable plastics can take between 1.8 and 2,500 years to degrade we can safely say that silicones are likely to take a while. (ACS Sustainable Chem. Eng. 2020)

Is silicone toxic? 

According to Health Canada, “silicone rubber does not react with food or beverages, or produce any hazardous fumes” and there are currently no known health risks associated with silicone cookware. They do however warn not to use silicone cookware at temperatures exceeding  220°C (or 428°F). 

[Even though the external applications of silicones are the focus of our coverage here at The Eco Hub, it must be noted that while deemed similarly safe, the FDA does warn about using liquid silicone as an injectable filler for cosmetic purposes. Liquid silicone may leave targeted areas blocking blood vessels in the brain, heart, lymph nodes or other parts of the body causing serious danger. (Healthline, 2019)]

A woman placing a vegetable into a silicone bag.

What are some of the benefits of silicone? (pros and cons) 

With that said, here are the pros and cons of using silicone products rather than single use products: 

Pros: 

  • Durable (scratch-resistant and shatter-proof)
  • Reusable 
  • Non-stick and easy to clean
  • Sealable
  • Safely heated (up to 220°C or 428°F)
  • Safely frozen (to – 60°C or – 76°F)
  • Accessible

Cons: 

  • More expensive
  • Not biodegradable 
  • Synthetic polymer 
  • Difficult to recycle 

Can you recycle silicone? 

Many people wonder if silicone plastic is recyclable and it turns out there are several ways to recycle silicone. You can start by contacting your municipal waste management services to see if they accept and recycle silicone products. Chucking our old silicone products in the bin and crossing our fingers can contaminate the waste stream and comes at cost to the waste management plant. If they do not accept silicone, you can look for companies like Terracycle to recycle old silicone products at a cost. 

Thankfully some companies are also beginning to offer take back programs for the silicone products they manufacture and sell to us. Once worn, you can return the products back to them for recycling. 

You also have the option of trying to recycle your worn silicone products at home by following these instructions

How bad is silicone for the environment?

It is hard to say but silicone is arguably an eco friendly option only in the context of the severe refuse problem that plagues our planet. By opting for silicone straws, silicone storage bags, silicone cupcake liners, or silicone menstrual cups, we divert waste from the waste stream for as many times as we use silicone alternatives instead of single-use products (plastic or otherwise). In doing so, we help to reduce the load on our landfills and on our ecosystems. Ultimately though, silicone is not the most eco friendly solution to our waste problem.

What’s the best way to recycle silicone? 

Most of the silicone that is recycled is turned into industrial lubricant oil or lower grade products. So the best way to recycle silicone seems to be whatever works best for you. As long as you are certain that it will be recycled properly, commit to whatever is within your means. 

A fridge with glass jars and silicone bags.

Is silicone more eco-friendly than plastic?

When compared to the commonly used plastics which are filling up our oceans, killing wildlife, and winding up in our food chain as well, silicone is definitely more eco-friendly than plastic. To start, silicone is a safe alternative to plastic since it doesn’t leach into food and drinks; it is safely reusable for far longer than other plastics because it is durable and non-toxic; it helps to divert waste to landfill (or ocean) by providing a reusable alternative, and is less likely to wind up as litter because it is reusable. 

What are the advantages of using silicone to replace single-use plastics?

By reaching for a reusable silicone straw (or any other silicone alternative to single-use plastics) every time we need one, we keep that many single-use plastics from our landfills, ecosystems, and wildlife. Silicone products are also a lot safer than commonly used plastics when it comes to temperature resistance and leaching. While some do not recommend heating food in silicone, silicone products remain a lot safer than single-use or generic plastic products.  

What is a good substitute for silicone?

Substituting for silicone all depends on what you are looking to substitute. For cookware, good substitutes for silicone include glass, ceramic, stainless steel, and beeswax wraps. You can even make your own DIY beeswax wraps if you are up for it. Compostable options (that are actually compostable) for things like cupcake liners and baking mats make wonderful biodegradable alternatives to silicone as well. 

When it comes to teethers, pacifiers, and nipples (teats), BPA-free silicone options may not have a more eco friendly alternative, but glass bottles (with a silicone sleeve), or bamboo and stainless steel dinnerware can make for healthier more eco friendly alternatives to silicone products designed for children. 

Is silicone biodegradable? 

While it may be disappointing for some to learn, silicones are not biodegradable; neither are they the answer to our non-stick dreams. They do offer wonderful benefits like durability and reusability that make them a safer alternative to other plastics. However, they are only an eco-friendly option in comparison to other plastics. 

So, if you do have to reach for silicone, don’t feel guilty if this is what works best for you. Making eco friendly choices is also about accommodating your needs and capacities, and we are equally about that too at The Eco Hub. Just remember to consider whether or not there are more eco friendly alternatives to what you are looking for, and whether or not you will be able to recycle the silicone item(s) you have selected once they are worn. 

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