In April 2017 researchers from Sweden and Italy published the results of their comparison of the labelling and content of hair dyes. A total of 52 hair dyes, from 11 different countries, were bought over the counter and analysed for p-phenylenediamine (a known allergen), toluene-2,5-diamine (a known human toxicant or allergen), and three oxidation products of p-phenylenediamine. Results showed that only 7 of the 52 products were incorrectly labelled. Differences in the geographical use of p-phenylenediamine and toluene-2,5-diamine was seen, with toluene-2,5-diamine being more common in European products and p-phenylenediamine more common in products purchased outside Europe. All dyes purchased in Europe contained p-phenylenediamine and toluene-2,5-diamine at levels within the limits defined by European legislation. However, levels were higher in some products purchased outside Europe. Only a small group of hair dyes sold in Europe were found to have been mislabelled.
Antelmi A et al. Evaluation of concordance between labelling and content of 52 hair dye products: overview of the market of oxidative hair dye. Eur J Dermatol. 2017 Apr 1;27(2):123-131