Cy
Cyclopentasiloxane
Cyclopentasiloxane · CyclomethiconeBarrier
The silicone behind a silky primer finish that disappears as it dries.
What it does
It’s a light silicone that evaporates after you put it on, giving many primers and moisturizers a silky finish without residue. It’s often paired with dimethicone: this one gives the slip going on, dimethicone the longer-lasting feel.
The evidence, graded
expert consensusUS safety reviewers found very little cyclopentasiloxane passes through skin. The data showed no sign that it irritates or causes allergy, and the reviewers judged meaningful exposure inside the body from cosmetic use unlikely. It and related cyclic silicones are used to condition skin and hair.Johnson 2011 · International journal of toxicology ↗
expert consensusSCCS/1549/15 (adopted March 2015, final July 2016) considered cyclopentasiloxane safe in cosmetic products at the reported concentrations, except in hair styling aerosols and sun care spray products, where air concentrations may exceed the level it considered safe. It said traces of D4, which the EU classifies as toxic to reproduction, should be kept as low as possible. The opinion does not cover oral care or the environment.SCCS 2015 · European Commission SCCS (adopted 25 March 2015, final version of 29 July 2016) ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
D5
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