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Siloxanes and Silanes graphicWhat Are They?

Siloxanes are synthetically manufactured chemical compounds that serve as building blocks of silicones. Silanes are modified silicon compounds.

Siloxanes are used in many different products, aiding in slip, which gives that silky, smooth feeling. Slip also helps products spread more easily, so it’s useful in deodorant, cosmetics, hair products, shaving cream, lubricants, and more. They’re also used as emulsifiers and smoothing ingredients. The biggest product category that shoppers will find these ingredients in is cosmetics, as well as lubricants in sexual health products. (By the way, keep an eye out for them in processed foods too.)

Silanes are much less common in personal care and cosmetics. When they’re used, they serve as skin conditioners, emollients, and coatings. Silanes can also be used as coatings for nanomaterial mineral sunscreens.

The Health Concern

One siloxane, cyclotetrasiloxane (D4) is toxic to aquatic life. D4 is also an endocrine disruptor and possible reproductive toxin. Other siloxanes have some evidence of endocrine disrupting capabilities, as well as other toxic effects.

Many siloxanes are persistent in the environment, meaning they stick around for too long without breaking down. And some are being evaluated by the European Union to potentially be classified as Persistent-Bioaccumulative-Toxic, or PBT.

One of the most commonly used siloxanes is polydimethylsiloxane, which also goes by the names dimethicone and PDMS. This ingredient is likely to bioaccumulate, which is the accumulation in the tissues of organisms. It is also likely to persist in the environment and be toxic to aquatic life.[i]

One of the more common silanes, triethyoxycaprylylsilane, is likely bioaccumulative, persistent in the environment, and toxic to aquatic life.[ii] More research is necessary.

There are many data gaps with these ingredients, and more research is needed. However, existing information makes them chemicals of concern. Siloxanes are often found on many restricted lists from authoritative sources around the world.

MADE SAFE evaluates each substance that is part of this chemical group individually. Because of data gaps and existing incriminating evidence, MADE SAFE exercises the precautionary principle looking not just at humans but the entire ecosystem, and will not allow these ingredients until more research is conducted.

Siloxanes and silanes are particularly useful in cosmetic and personal care formulations, and because there are very few alternatives, formulating without them is tricky. Brands offering MADE SAFE certified products have worked hard to find suitable alternatives that still bring shoppers the product feel and application they want without these ingredients.

How to Avoid Them

  • On labels, look for “siloxane,” “ethicone” and “silane” as suffixes on ingredient names (ex: cyclotetrasiloxane, dimethicone, triethyoxycaprylylsilane).
  • Be on the lookout for these ingredients, as they’re widespread, but pay special attention to cosmetics and sexual health products. (And check food labels too!)
  • Choose non-nanomaterial sunscreen. There are many reasons to choose non-nano, one being that silanes can be used as coatings for nano-sized mineral sunscreen ingredients like zinc oxide.
  • Choose MADE SAFE certified products, which do not contain siloxanes or silanes, as well as numerous other substances known or suspected to be harmful to people or the planet.
  • Follow #MadeSafeBeauty, our social media campaign designed to bring awareness to the fact that trendy packaging claims like “clean” and “better” can be deceiving. #MadeSafeBeauty products are made with the safest ingredients meaning no siloxanes or silanes.

[i] US EPA. 2019. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11. United States Environmental Protection Agency, Washington, DC, USA. Available from https://www.epa.gov/tsca-screening-tools/epi-suitetm-estimation-program-interface

[ii] US EPA. 2019. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11. United States Environmental Protection Agency, Washington, DC, USA. Available from https://www.epa.gov/tsca-screening-tools/epi-suitetm-estimation-program-interf

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