Silicones are synthetic molecules based on silicium (one of the most abundant elements on Earth, also present in the human body, especially in the connective tissue) and oxygen.
The reaction of silicium and oxygen, through suitable chemical processes, makes many polymers with long structures.
Depending on the organic chemical group and on polymerization parameters, silicones come in very different structures and textures, from liquids (oils) to rigid ones including viscous, resinous, doughy or waxy substances …
The word "silicone" does not apply to a specific ingredient, but to a large family of products with particular proprieties…that are widely appreciated in cosmetics.
Efficient from skin to hair
Silicones are widely used in hair products. Indeed, they can coat a resin, sheath hair fibers, style hair, give smoothness, ease hair detangling or give hair silky-smoothness and shininess.
Not that easy nowadays to find an efficient hair care product (shampoo, conditioner, gel or foam) without silicones!
Further, they are also found in many face care creams, to which they give fluid and soft textures, pleasant to the touch and easy to spread on the face.
Their organic silicium content helps to offset a deficiency which increases along ageing (from 30-35); silicones strengthen the skin resilience and tonus, which make them an attractive ingredient for anti-ageing products.
A high cutaneous tolerance
Silicones are renowned to be well tolerated by skin. They are not comedogenic. As per animal testing, no potential irritant effect exists either for the eyes or for skin.
They are not sensitizing, even if extremely rare cases of allergy to silicones have been reported.
Considered as safe for use, but …
First, a harmful risk by inhalation is almost insignificant, added to the fact that silicones are almost never an ingredient of products applied by spraying.
Due to the large size of the molecules, silicones are not prone to enter the cutaneous barrier. Nevertheless, data from some studies make it possible that skin absorbs up to 0.5% of the silicones present in a cosmetics.
However, if this figure is of no consequence for many silicones, it could be another song for the cyclomethicones family ( Cyclomethicone itself, and also Cyclotrisiloxane , Cyclotetrasiloxane , Cyclopentasiloxane , Cyclohexasiloxane , Cycloheptasiloxane …).
Indeed, these last ones are listed in the CMR (Carcinogen, Mutagen or harmful for Reproduction ingredients) Class 2 as substances suspected to be harmful for the human reproduction. Nevertheless, an SCCS report, issued on 22 June 2010 cleared these substances of any risk for the human health when used at the rates commonly seen in cosmetics.
The environmental risk
However, in this same report, the Committee requires the European Commission to study the environmental risk linked to their use in cosmetic products …
The cyclomethicones family is also classified as a potential risk for aquatic life. Furthermore, silicones as a whole, which are poorly biodegradable, are considered as pollutant for the environment.
Can we do without silicones?
They are often said as being irreplaceable, especially due to a lack of substitutes as efficient while being from natural origin. This is a true brainteaser for the organic cosmetic industry, which does not want to use silicones, and has yet a long way before having efficient hair care products.
Recently, a "vegetable" silicone has been marketed as an ingredient for cosmetics. Produced from algae through a biotechnology, it is an attractive substitute…though not yet often found in the beauty and hygiene products we use every day!