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