Grey Hair or Allergy?
Hair colouring products are thought to pose one of the biggest risks of serious allergic reaction of all categories of consumer products. In addition to containing components that can trigger allergies, all of these products are poisonous should they be digested. PPD (p-phenylenediamine) is one of the most common active ingredients in conventional hair dyes and it is believed to be a leading cause of hair dye allergic reactions. Ammonia, hydrogen peroxide and diaminobenzene are other common components of traditional hair dyes that are alleged to cause severe allergies.
Progressive hair colorants are the alternative to conventional hair dyes and are suitable mainly for men. But they can also be harmful. They either contain a metallic component, such as lead acetate, or bismuth citrate or organic substances. Both lead and bismuth are heavy metals and thus feared to be poisonous, though bismuth and its compounds seem to be the better choice of the two. The concentration of metallic compounds in hair colouring products should not exceed 0.4%-0.6%, depending on the country of distribution. However, heavy metal compounds, contained in progressive hair colorants, seem to be less allergenic than organic compounds used in regular hair dyes.
Some organic-based types of hair colorants, such as Touch of Gray, also contain the aforementioned PPDs. Another organic-based progressive hair colorant, Poly Re-Nature, uses 5,6 dihydroxyindoline as its main active substance, which has been approved for use in hair colorants at concentrations below 2%. Poly Re-Nature also contains ammonia, which is thought to be the second most frequent cause of allergic reactions after PPD.
No matter which approach you take, it seems that you cannot avoid using poisonous or allergy-triggering chemicals if you wish to colour your white hair. Natural hair dyes such as Henna offer no solution either. Besides their many practical limitations, natural hair dyes are known to be extremely allergenic. If you decide to go ahead and dye your hair, no matter which product you chose, make sure you follow the guidelines for correct application and use a patch test before you apply any of these substances.