FUNCTIONS OF CHEMICALS IN HAIR DYE
Hair dyes contain a long list of chemical ingredients. How can we know what chemicals pose more potential health hazards than others?
A material safety data sheet (MSDS) or product safety data sheet (PSDS) provides information on a substance or combination of substances such as chemicals, chemical compounds or mixtures.
What could be the top nasty chemicals in hair dye products which pose potential health hazards? If they are bad, then why do they form part of the ingredients? It is simply because each of them is needed for a reason.
Here is a list of their functions (in full concentrations in most cases or otherwise stated) for our awareness. Take note that some chemicals have synonyms. The best way to identify a chemical is by its CAS number.
1. Ammonia CAS# 7664-41-7
Due to its high alkalinity, it lifts the hair cuticle up to let the molecules of the dye in. The cuticle protects the integral structure of the hair fibre. The pigments that give natural hair colour are below the cuticle. The cuticle needs to swell to allow the hair colour to get to those natural pigments and deposit new colour.
It is corrosive to our respiratory system through inhalation. It is also very toxic to aquatic organisms.
An alternative to ammonia is monoethanolamine.
2. Para-phenylenediamine (PPD) CAS# 106-50-3
PPD is used in hair dye because it is a permanent dye that gives a natural look, and the dyed hair can also be shampooed or permed without losing its colour.
It may cause an allergic skin reaction.
3. Resorcinol CAS# 108-46-3
The dye formation reactions occur by primary intermediates (such as p-phenylenediamines) with couplers such as resorcinol and m-aminophenols to attain the final hair colour.
4. Parabens CAS# 99-76-3
Parabens are commonly-used preservative against bacteria and fungus in personal care products.
Studies have shown parabens to potentially increase risk for breast cancer.
5. Toluene-2,5-Diamine CAS# 615-50-9
It is a less aggressive alternative to PPD to activate the colouring pigment.
However, it is a cancer suspect agent/suspect carcinogen (listed as Toluene 2,4-diamine CAS# 95-80-7).
6. Hydrogen Peroxide 20%–40% CAS#7722-84-1
Hydrogen peroxide is an oxidising agent. It oxidises melanin, organic compounds which absorb visible light and give hair its colour. It also oxidises other chemicals in the dye mixture, to result in the chemical compounds that bond to the hair as dyes.