Silicone is Plastic

Fulfilling your commitment to avoid plastic toys takes a rather sophisticated knowledge of materials science, which classifies man-made materials into four basic categories: metals, polymers, ceramics and composites. The materials we know as plastics fall into the category of polymers, and while the word “plastics” is most often used to refer to polymers synthesized from fossil fuels, the technical definition—a group of materials, either synthetic or naturally occurring, that may be shaped when soft and hardened to retain the given shape—certainly includes polymers like silicone, which are made from a synthetic, rubber-like substance known as siloxane.

The main difference between these two polymers is found in their distinct chemical compositions. In general, polymers are made by linking molecules known as monomers together, with the process dependent on the properties of the elements that make up those monomers. The materials we typically think of as plastic are made up of monomers comprised of hydrogen and carbon while silicone is made up of monomers comprised primarily of silica and oxygen, although they also contain hydrocarbons.

Making silicon from silica is the first step in the process; this chemical is then heated and reacted with fossil fuels to make siloxane. Once you understand how silicone is made, it becomes clear that it is just as synthetic as any other form of plastic and that, while it is not made entirely from fossil fuels, chemicals made from coal and natural gas are required to manufacture it.

As far as how silicone behaves in the environment, it is as persistent as plastics made from fossil fuels and it is known to leach toxic chemicals, which is why the European Chemicals Agency has listed the grades of silicone known as D4, D5, and D6 as persistent, bioaccumulative, toxic substances that should be phased out of use.

Anyone touting silicone as a safe, eco-friendly substitute for fossil fuel plastics has been misled by the greenwashing used to sell this material. Now that you know, share your knowledge and help achieve the discontinued use of this and any other synthetic material that harms our natural world.