We will keep this guide to a summary and a short comparison, as we’ve already discussed the potential answer to this question across this FAQ style guide about silicone.
Summary – Is Silicone More Sustainable Than Plastic?
The answer to this question can differ depending on who you ask. At the very least, it can be controversial
Overall, silicone might be slightly more sustainable than plastic in some ways, but it can also present some of the same sustainability issues as plastic in other ways
You might like to minimize your use of both materials if possible, but for some uses such as leak proof lids for food containers, a high quality food grade silicone might be the better material
The answer can be product and company specific too – not all companies make their silicones to the same standard, or in the same way with the same chemistry
Just as one example, a high quality food grade silicone that meets safety regulations, is recyclable, will last many years and uses, and is filler and toxic chemicals free (and that does not leach), is probably more sustainable than most regular plastics
But, it’s also hard to get a true gauge on silicone’s actual sustainability score as there aren’t any comprehensive life cycle assessments (that measure different sustainability indicators) done on it that we could find
*This is just a generalised guide. Each plastic and silicone product is going to present it’s own pros and cons in terms of sustainability depending on what it is made of, and other sustainability measures like how it’s made and how waste can be managed.
Plastic vs Silicone: Comparison
The main difference between plastic and silicone is:
… most plastics have a polymer backbone of hydrogen and carbon, [but] silicones have a backbone made of silicon and oxygen, and hydrocarbon side groups (lifewithoutplastic.com via bettermeetsreality.com)
From a sustainability perspective, the differences and similarities are:
What They Are Made With – Plastics are generally made from fossil fuel feedstock (fossil fuels being a non renewable resource). Silicone is made with the abundant natural resource, silicon. But, is also usually made with hydro carbon groups (methyl groups) from fossil fuels too.
Break Down & Degradation – One of the problems with both materials is that they don’t really break down like organic materials and natural materials do (both plastic and silicone are synthetic materials). Plastic might be worse though because it breaks down into micro plastic and nano plastic.
Leaching Of Chemicals For Humans – both materials can have leaching issues with fillers, additives and chemicals, but, food grade silicone might have less leaching issues than most plastics (with some food grade silicones even claiming to have no harmful or toxic chemicals). One source says if you pinch silicone ‘pure silicone does not change color at all, so if any white shows through, there may be fillers in your product.’ (earthhero.com)
Impact In The Environment – Plastic can have a range of negative effects in the environment. Various sources say silicone compounds can be prevalent in the environment too (wikipedia.org via bettermeetsreality.com), but probably less than plastic, especially in the area of micro plastics
Recyclability – neither material has high recycling rates. Although some types of plastic in some countries, and some specific silicone brands, do get recycled. Most silicone often can’t or wont be recycled through regular municipal recycling streams, and plastic often has it’s own issues with contamination, and so on
Biodegradable – neither material is biodegradable
Material Lifespan In Use – various sources say high grade silicone usually lasts longer than regular plastics, and resists deterioration (clearandwell.com). So, this averages out it’s environmental footprint somewhat
If Not Silicone, Then What To Use?
Silicone may actually be the best option for specific uses like leak proof food container lids in some instances (compared to plastic … and, it helps if it’s a guarantee the silicone won’t leach and contains no bad or harmful chemicals)
It’s also possible that as a re-usable material, silicone can come out on top of other materials (especially single use or limited use materials) if used enough times
But, for other applications and products, look for alternative materials where available/possible, that either come completely from natural renewable resources (that aren’t synthetic and that don’t have additives or fillers), have a high recycling rate, are biodegradable or compostable. Stainless steel might be one example
The Sustainability Of Plastic
Read more specifically about the sustainability of plastic in this guide.
Other Factors To Consider
Just as there is different types of plastic, there are different types of silicone. Each different type of silicone can have a different sustainability footprint
Using recycled silicone for new silicone products is something which we didn’t explore in this guide
The waste management systems, facilities and technology in a given country or State make a difference to the sustainability not just of different materials, but different waste items and products (because of how different waste materials and items are processed among the different disposal options at different rates)
How long a silicone product or item lasts, or how many times it can be used/re-used before being thrown out, impacts it’s sustainability footprint