Evaluation of concordance between labelling and content of 52 hair dye products: overview of the market of oxidative hair dye

Non‐oxidative hair dye products on the European market: What do they contain?

“…The results from this study may serve as a basis for future developmental work with the aim of identifying and quantifying some target substances of interest in non‐oxidative products. p ‐Phenylenediamine and toluene‐2,5‐diamine have been target substances for chemical analysis of oxidative hair dye products . One study found that these substances were incorrectly labelled on 13% of the products, which, however, were from several continents .…”

“…In our study, 3 of 398 initially selected products used the terms “may contain” or “+/−”, which are not allowed for hair dye substances according to the Cosmetics Regulation. This was, however, a smaller fraction than found in other studies . Another limitation is that the selection of products might not have been representative.…”

“…p-Phenylenediamine and toluene-2,5-diamine have been target substances for chemical analysis of oxidative hair dye products. 8,18 One study found that these substances were incorrectly labelled on 13% of the products, which, however, were from several continents. 18 In our study, 3 of 398 initially selected products used the terms "may contain" or "+/−", which are not allowed for hair dye substances according to the Cosmetics Regulation.…”

Evaluation of in vitro testing strategies for hazard assessment of the skin sensitization potential of “real‐life” mixtures: The case of henna‐based hair‐colouring products containing p‐phenylenediamine

“…For instance, PPD can be involved in autoxidation and/or oxidation reactions with other ingredients (eg, RSC and m ‐aminophenol, which are coupler agents that were mentioned on the labels of some “henna cosmetics”), producing a series of reactive dimers and trimers or other reaction products . Moreover, on the labels of the manufacturers’ henna products for eyebrow colouring (products 8, 9, and 10), it was stated that, before application, the user needs to mix them with a solution containing hydrogen peroxide, which is an oxidizing agent whose reaction with PPD is well known to form possible allergen products, such as p ‐nitroaniline and 4,4‐azodianiline . Although this condition (henna + hydrogen peroxide) was not investigated here, our study provides an analysis of the toxicological impact of the henna cosmetics adulterated with PPD as well as the presence of other synthetic ingredients declared on the labels of some products.…”

“…22,67 Moreover, on the labels of the manufacturers' henna products for eyebrow colouring (products 8, 9, and 10), it was stated that, before application, the user needs to mix them with a solution containing hydrogen peroxide, which is an oxidizing agent whose reaction with PPD is well known to form possible allergen products, such as p-nitroaniline and 4,4-azodianiline. 68 Although this condition (henna + hydrogen peroxide) was not investigated here, our study provides an analysis of the toxicological impact of the henna cosmetics adulterated with PPD as well as the presence of other synthetic ingredients declared on the labels of some products. Thereby, the connection to contact allergy potential of the potentiation effects between henna and synthetic allergens added to the cosmetics and the reaction products formed cannot be ignored.…”