Cyclopentasiloxane vs Formaldehyde (free): which is worse?
Quick answer: Formaldehyde (free) carries the heavier risk profile. Cyclopentasiloxane is restricted in the EU and allowed in the US; Formaldehyde (free) is banned in the EU and allowed in the US.
| Property | Cyclopentasiloxane | Formaldehyde (free) |
|---|---|---|
| EU status | Restricted | Banned |
| US status | Allowed | Allowed |
| Risk level | medium | high |
| Banned in | — | European Union |
| Restricted in | European Union | — |
| Category | endocrine disruptor | cmr |
| Where it hides | hair serum, primer, deodorant | nail hardener, keratin treatment, eyelash glue |
What is Cyclopentasiloxane?
Cyclopentasiloxane is a volatile silicone (D5) used for smooth, silky texture.
What is Formaldehyde (free)?
Formaldehyde (free) is free formaldehyde used directly as a preservative and in salon hair treatments.
Documented risks
Cyclopentasiloxane: Persistent and bioaccumulative; the EU restricts D5 in wash-off products over environmental and endocrine concerns. The US has no restriction.
Formaldehyde (free): A known human carcinogen (IARC Group 1). Banned from direct use in EU cosmetics; allowed in US products with limited oversight.
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