Walk into any homeware store and you can almost guarantee that the kitchen and baking section will be full of silicone. This flexible, mouldable material is a popular alternative to plastic and is used to make everything from spatulas to cupcake cases.
Many in the low waste movement have been quick to embrace silicone too. It is often used to make reusable alternatives to single use items – you can even find silicone straws and dish sponges now.
But is silicone really an environmentally friendly alternative? In this article, we’ll look at how this popular material stacks up and whether it has a place in an eco-friendly home.
What is silicone and how is it made?
You have likely heard before that silicone is made from sand. This is true, but the full picture is a little more complex.
One of the raw materials used to make silicone is silica, also known as silicon dioxide, which is indeed found naturally as sand. Quartz sand if you want to be exact. But it is a long journey from a handful of sand to a silicone spatula.
First, the sand is heated to very high temperatures in the presence of carbon (usually coke, which is made by heating coal without any air). This is done to turn the silica into the element silicon, by burning off the oxygen, which combines with the carbon and is released as carbon dioxide.
The silicon produced by this process then undergoes further chemical reactions depending on what it will eventually become – silicon is often used in computers, for example. But we are interested in how it becomes silicone rubber, which is the form we most often find in our homes.
To create the soft, rubber-like silicone that is used for many home goods, the silicon undergoes several different chemical processes, which include polymerisation – the same process that is used to make plastics from hydrocarbons or plant cellulose. The polymerisation process used to make silicone includes the use of hydrocarbons derived from fossil fuels, such as oil or natural gas.
So, although we started with a natural raw material (sand), silicone isn’t considered a natural material itself. Instead, it is usually viewed as falling somewhere between a synthetic rubber and a plastic.
What is silicone used for?
Once it has been transformed into silicone, this material can easily be moulded into a wide range of different items. Because it is heat stable – meaning it will hold its shape even at high temperatures – silicone has become a favourite in our kitchens. You can find spatulas, baking tins, cupcake cases, oven tray liners, and even oven mitts made from silicone.
Because it can be made stretchy and pliable, silicone has also gained popularity as an alternative to clingfilm for storing food. You can often find stretchy covers made from silicone that can be used to cover bowls and containers.
It is more durable than plastic too and is used to make longer lasting, reusable alternatives to disposable items like straws or sandwich bags. The lids and sleeves of reusable coffee mugs are often made from silicone as well.
Another reason that silicone is popular for cooking and food storage is that it is thought to be safe for human health. Unlike plastics, which can leach dangerous chemicals into our food, silicone is stable even when exposed to high or low temperatures. Plus, it is easy to clean. As a result, it is often used to make items for babies and young children – bibs, teething toys, and even baby tableware and toothbrushes are often made from silicone.
You might even see silicone used to make jewellery – because it is easy to mould and colour, plenty of jewellery designers use it to make statement earrings, necklaces, and bangles. Those colourful wristbands that are often used by charities or for company branding are usually made from silicone too. And you can also find silicone phone cases.
Is silicone environmentally friendly?
Silicone does have some plus points when it comes to eco-credentials. It is often used as an alternative to plastic with good reason. It is more durable, meaning that it lasts longer and doesn’t break down into microplastics that contaminate our oceans.
When used as an alternative to disposable items such as clingfilm, coffee cup lids, or plastic straws, silicone items help to reduce the amount of plastic that we send to landfill.
So, as an alternative to plastics – especially single-use plastics – silicone does seem to be the more environmentally friendly choice. However, it has several drawbacks too that you might want to consider before choosing silicone as an eco-friendly option for your home.
Technically, silicone is recyclable. But not usually via your normal recycling collector. Most kerbside collection schemes won’t accept silicone items, unlike plastics, which you are increasingly able to include in your home recycling bin.
This means the vast majority of silicone items will end their lives in landfill. Being a durable item is a plus in that it prevents silicone from breaking down into microplastics, but it also means that it doesn’t biodegrade.
Although it takes a bit of extra effort, there are specialist recycling schemes that will accept silicone items. TerraCycle’s Zero Waste Kitchen box is one example.
The recycling pathway for silicone isn’t necessarily ideal though. Unlike metals or glass, which can be recycled again and again, silicone usually becomes an oil which is then used as a lubricant for industrial machines. So, your spatula might have a second life, but only a brief one.
Having said that, some brands are looking to address the issue of recyclability by accepting silicone products back at the end of their useful life. Watch manufacturer, Ksana, for example, encourage customers to return their silicone watch straps so that they can be recycled into insulation for solar panels.
Unlike plastics, which have been found to leach endocrine-disrupting chemicals such as BPA or BPS into our food, silicone seems to be mostly safe for storing food. There have been fewer studies on it so far though and one study did find that a limited amount of siloxane was released from silicone-based kitchen products when they were soaked in ethanol for 72 hours.
Siloxanes are a concern because they are a potential endocrine disrupter. However, silicones are generally considered safe, as long as they are food or medical grade. Most of us don’t store our silicone bakeware in ethanol anyway – and that same study found no siloxanes in either milk or baby formula after they were exposed to silicone for 6 hours.
From a safety point of view, it is also worth noting that cheaper silicone products often include other chemicals as a filler. If you are choosing silicone for an item that will be coming into contact with food (or your baby’s mouth), always look at the grade – it should be at least food grade, ideally medical grade so that you know it is safe.
Another way to tell if chemical fillers have been used is to bend or twist the item to see if any white appears. Silicone will be coloured all the way through, so any white appearing indicates that fillers have been used.
Sand is a natural resource but isn’t renewable in the way that wood or other plant-based materials are. Having said that, silica is a plentiful resource – one of the most common minerals on earth.
Silica is mined in many different places around the world. But the silica dust created by mining can be a concern for human health – long-term exposure to the dust has been linked with lung cancer and other respiratory diseases. Where mines are not responsibly managed, there is concern that the silica dust might pollute the air, causing health risks for residents as well as workers.
One 2015 study into silica mining in India found that illegal mining in the region was contributing to air pollution and environmental degradation. Even when well-managed, open-cast silica mines cause a loss of local habitats and topsoil while in use. The impact may be smaller if the land has a proper ecological management plan in place to restore it once the mine closes – in the case of illegal mines though, this is usually not the case.
It is worth noting that not all silica is mined for use in silicone – it has many uses including in glassmaking and ceramics. And extracting most natural raw materials will create some kind of environmental impact.
When it comes to sustainability, most of us are well aware of the need to reduce our reliance on fossil fuels such as oil, coal, and natural gas. Not only are these a non-renewable resource, but burning them releases greenhouse gases, contributing to climate change.
At first glance, silicone should come out well ahead of traditional petroleum-based plastics, since its core raw material is silica rather than crude oil. But, as we saw when we looked at the manufacturing process, producing silicon from silica and then turning that silicon into silicone both require the use of hydrocarbons derived from fossil fuels.
For this reason, the manufacture of silicone is not an environmentally friendly process. It is also fairly energy intensive, because of the high temperatures needed to extract the silicon.
So, is silicone a better alternative?
Like so many things when it comes to trying to live an eco-friendly life, the answer to whether silicone is an environmentally friendly option depends on what the alternatives are.
When it comes to choosing reusable silicone products over single-use plastics, silicone is the better choice. And it generally scores better than plastic for longer use items too, especially from a health perspective.
But there are some concerns with silicone in terms of its manufacturing process and lifecycle that might make other products a better option.
Where other eco-friendly alternatives are available, you might do better to reach for them over silicone. For example, you could choose glass, metal, or ceramic cookware for baking and wooden spoons over silicone spatulas.
Bamboo, glass, or metal straws might be preferable to silicone ones. Beeswax wraps could replace clingfilm and plastic storage bags instead of silicone covers. And you can also find glass or metal containers for storing and transporting food.
For baby items, you might be able to find alternatives made from natural rubber, which shares many of the same properties as silicone – it is durable, easy to clean, and non-toxic. But it is also biodegradable and is made by tapping the sap of rubber trees, making it a sustainable option.
Natural rubber isn’t without its issues however, – when harvested irresponsibly, it can drive deforestation. And there’s not enough available to fill the world’s current needs for rubber. But, when responsibly sourced, natural rubber can be a good alternative to synthetic rubbers like silicone.
It can be hard to find non-plastic alternatives for every item though, and silicone is often the only available option. In which case, make sure to choose a food or medical grade silicone without any chemical fillers. Keep the item as long as you can and, when it can no longer be used, try to seek out recycling schemes rather than sending it to landfill.