Awasome Formaldehyde In Hair Color Ideas. Web if you have to colour your hair while pregnant, then use the safest natural hair dyes you can find ;e.g. Web osha has found that many hair smoothing products contain formaldehyde, formaldehyde dissolved in water (called methylene glycol), or other chemicals that can release.
Web if you have to colour your hair while pregnant, then use the safest natural hair dyes you can find ;e.g. Web hair smoothing products, also referred to as hair straightening products, may release formaldehyde gas, a known human carcinogen, when heated. It reacts with the peroxide.
