I created the below ranking according to the least harmful ingredients:

hair dyes 2

In the cases where the information was inexistent online, I left the cell blank and ranked the product lower in that regard.

 

Explanation of the columns:

  • P-Phenylenediamine (PPD) is one of the most dangerous ingredients found in hair dyes. It can cause really severe alergic reactions. More info here. Photos of people who had alergic reactions to PPD here. The European Comission considered N,N’-bis-(2-hydroxyethyl)-2-nitro-p-phenylenediaminenot safe for use” and that hydroxyethyl-p-phenylenediamine sulphate “poses a risk to the health of the consumer”
  • Toluene is alergenic. More info here. Toluene-2 5-Diamine Sulfate is less risky than Toluene-2 5-Diamine as the European Union “results indicate that patch test reactivity is higher to toluene-2,5-diamine than toluene-2,5-diamine sulphate”. The European Union considers that both Toluene-2 5-Diamine and its sulfate are “safe with regard to systemic toxicity” but warns that “Toluene-2,5-diamine is an extreme skin sensitiser. The frequency of allergic reactions in hairdressers and consumers remains a considerable concern for consumer safety”. Regarding 4-amino-2-hydroxytoluene, the comission considers that it “does not pose a risk to the health of the consumer, apart from its sensitising potential.”
  • Resorcinol is alergenic. More info here. The European Comission considered that Resorcinol “will not pose a risk to the health of the consumer, apart from its sensitising potential”, 2-methylresorcinol “does not pose a risk to the health of the consumer apart from its skin sensitising potential” and that 4-chlororesorcinol does not pose a risk to the health of the consumer, apart from its moderate skin sensitising potential.
  • Ammonia is a corrosive agent that can damage the hair cuticle and therefore cause your hair to break. Ammonia also reduces your hair’s ability to mantain its natural pigment (color). More info here.
  • Peroxide is the ingredient that causes the oxidation, breaks up your hair’s melanine (natural color) and let’s the other ingredients enter inside your hair structure (it’s what allows the dye to be more permanent). Peroxide therefore weakens your hair shaft which can lead to breakage. It can also kill your hair follicles and, therefore, make your hair start falling down. More info here
  • Short-chain alcohols are used to help the dye dry faster. They also dry out your hair. More info here, here and here.
  • Non-soluble silicones are used as a coat on the hair to give it an healthier appearance. But it’s just appearance because, in fact, this silicone coating doesn’t allow your hair to get moisture and protein. It can also cause breakage of the hair. More info here. Dimethicone is worst than amodimethicone.
  • The number of potencially dangerous ingredients (column before last in the table) is the number of red and dark orange ingredients listed here. I counted how many times they appear, regardless if they were repeated or not (ex: if a red ingredient was present both in the developer and in the color dye, I counted it as 2).

 

Important notes:

  • The ingredients are different from colour to colour. For instance, the number one in the ranking would drop to the bottom of the table if we analysed the color Edelmahagoni (t876) instead, because in this colour it has N,N’-Bis(2-Hydroxyethyl)-2-Nitro-p-Phenylenediamine (PPD).
  • Schwarzkopf Brillance Glanz-Tönungs-Gel can not be used on bleached hair.

 

In summary, ranking of worst ingredients:
1) N,N’-bis-(2-hydroxyethyl)-2-nitro-p-phenylenediamine
1) hydroxyethyl-p-phenylenediamine sulphate
2) Toluene-2 5-Diamine (score 8 at EWG)
3) Toluene-2 5-Diamine sulfate (score 8 at EWG)
4) Resorcinol (score 8 at EWG)
5) 4-chlororesorcinol (score 6 at EWG)
6) 4-amino-2-hydroxytoluene (score 5 at EWG)
7) 2-methylresorcinol (score 4 at EWG)
8) Ammonia
9) Peroxide
10) dimethicone
11) amodimethicone
12) Alcohol Denat
12) Isopropyl Alcohol
12) methyl alcohol