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Cyclopentasiloxane

Worth a closer look

Evidence key Strong Moderate Weak How we grade

Suspected endocrine disruptor

What it can be used for
Conditions hair, conditions skin, dissolves other ingredients and softens skin (the functions the EU ingredient database, CosIng, lists for it; a product may use it for any of them)
CAS number
541-02-6

Why it’s flagged

  • Under EU evaluation as an endocrine disruptor, or identified as one by a national authority (ED Lists II and III).

    EU ED List II: under evaluation as an endocrine disruptor in an EU process. List III: identified as one by a national authority in the EU.

What the research says

  • A common personal-care-product ingredient can appear on ingredient labels under several different chemical names (the silicone D5 may be listed as 'cyclopentasiloxane' or 'cyclomethicone'), which may not read as the same substance to a consumer trying to identify or avoid it. Moderate evidence. Coggon 2018

Each finding shows its evidence grade. See every graded fact or how we grade.

What this page can’t tell you

These lists describe what a substance can do, its hazard. The risk from one product depends on how much is in it and how you use it, and the label doesn’t say how much.

Not being on a list doesn’t make an ingredient safe. It may never have been assessed.

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Flagged the same way

Official lists checked September 2026. Spotted a mistake? Tell us.