Methylene Glycol
Notable concerns
INCI · Methylene GlycolCAS 463-57-0
Also known as: Methanediol · Formaldehyde monohydrate
PreservativeConditioning
In plain language
The liquid form of formaldehyde (created when formaldehyde gas dissolves in water), famously used in 'Brazilian Blowout' hair straighteners.
Releases massive amounts of carcinogenic formaldehyde gas when heat (like a flat iron) is applied.
Where it can be sold
Simplified regulatory status by market — for guidance, not compliance advice.
European UnionNot permitted
Regulated identically to formaldehyde; banned from cosmetic use.