What You Need to Know About Silicone
Silicone is the new plastic. Now people know the dangers of BPA in plastics, they’re wising up to using it, BUT is the swap to silicone a safe one? Let’s discuss.
so what exactly are silicones (or siloxanes)?
The plastics industry considers silicone a plastic, and I agree, regardless of much of the green marketing claiming it is not a plastic!
Many people think silicone is a natural material derived directly from sand. WRONG. Silicones are synthetic and include a mix of chemical additives derived from fossil fuels. The key difference from common plastic is that silicones have a backbone made of silicon.
There are three substances to understand:
Silica: the raw material used to make silicone resins. Beach sand is practically pure silica.
Silicon: This is the base element that makes up silica, but silicon is not generally found in nature in this elemental form. It is made by heating silica at very high temperatures with carbon in an industrial furnace.
Silicone (siloxane): The silicon is then reacted with fossil fuel–derived hydrocarbons to create the siloxane monomers which are bonded together into polymers. The quality of these silicones can vary greatly depending on the level of purification done.
what we know
Silicones are NOT completely inert and stable as people claim. They can release toxic chemicals at low levels, and the leaching is increased with fatty substances, such as oils.
Silicone bakeware and nipples contain cyclic siloxanes (D4, D5, D6) that can migrate (PMID: 22575024).
Siloxanes are released from silicone bakeware, with leaching increasing as the food fat content increased. https://hal.science/hal-00577342/document
Heating new silicone moulds drives release into indoor air (substantial levels of volatile methylsiloxanes), emissions dropped after a few uses (PMID: 30798195)
Coated baking papers can transfer siloxanes to baked goods during heating (PMID:27041660).
Silicone tubing commonly used for medical applications has been shown to leach several chemicals, including dioctyl phthalate (PMID:16563675). And silicone intravenous devices have been shown to leach silicone and cause local inflammation (PMID:10373141).
cadmium + heavy metals in silicone
How is cadmium sneaking into silicone?
Cadmium-based pigments/dyes (bright reds, oranges, yellows) are used in cheap plastics and rubbers, so low-quality silicone kitchenware, toys, or pacifiers made with recycled materials may contain them. Cheap fillers added during manufacturing can also be contaminated with heavy metals.
How to avoid heavy metals in silicone
Avoid off-brand silicone kitchen products, especially coloured bakeware from markets without strict regulations.
why does it matter?
Cadmium is highly toxic: It accumulates in the body, affecting kidneys, bones, and the nervous system, and is classified as a human carcinogen.
Children are especially vulnerable.
Cadmium can migrate into food when silicone is heated, especially fatty foods (the same conditions that increase siloxane migration).
safe silicone use
If you are going to use silicone, be sure it is high quality, food grade or medical grade silicone and does not contain any fillers.
I consider silicone a safer alternative to Teflon and non-stick cookware (perfluorinated chemicals), but I would opt to use it only when there is really no other choice! There are too many excellent glass and stainless steel options for cooking and baking, it’s not worth the risk!
Reserve silicone for cold/room-temp uses (freezer molds, snap lock bags, lunchbox cups, gelatin gummies etc).
Skip silicone-coated parchment papers for long, hot bakes; use uncoated parchment or glass/metal instead. I occasionally use silicone coated unbleached parchment paper (if needed) and don’t sweat it.
Medical grade silicone in menstrual cups (as they’re not heated) is likely OK.
I do still prefer silicone for drinking straws for kids (saftey).
pinch and twist
To test a product for fillers you can pinch and twist a flat surface of it to see if any white shows through. If so, a filler likely has been used. You will have no idea what the filler is and it may leach unknown chemicals into the food.
The pinch test should not be relied upon as the sole basis for determining the safety of a silicone product however. The best way to determine the safety of silicone is to look for certifications by a reputable agency. LFGB tested is the best to look for, but FDA certified is OK too.
the takeaway
Given that there is so little safety data on the use of silicone bakeware, and the availability of other types of cookware that are non-toxic, more eco-friendly, and actually safe, I’d recommend ditching silicone in bakeware then wherever else you can as your budget allows.
Lowest concern: Medical-grade silicone and LFGB tested (migration is minimal when not heated or degraded).
Higher concern: Heating silicone (bakeware, spatulas, coated paper) and imported poor grade silicones (made in China).
Don’t forget to check your personal care products! Lotions, hair serums, deodorants often contain D4–D6; these can be absorbed via skin and inhaled.
