EU Scientific Committee to present safety opinions on a potentially genotoxic hair dye
11 Oct 2022 --- The European Committee (EC) is seeking the Scientific Committee on Consumer Safety’s (SCCS) opinion on the safe use of the hair dye Hydroxypropyl p-phenylenediamine and its dihydrochloride salt. This is the second submitted request on the compound, with the first one adopted in 2019.
The SCCS has nine months to present its conclusion, starting from September 20 with a 20 June 2023 deadline.
Hydroxypropyl p-phenylenediamine and its dihydrochloride salt are cosmetic ingredients that dye hair. However, they are currently not regulated under Cosmetic Regulation 1223/2009.
In its request, the EC asks whether the SCCS considers “Hydroxypropyl p-phenylenediamine and its dihydrochloride salt safe when used in oxidative hair coloring products up to a maximum on-head concentration of 2%.”
SCCS previously concluded that hydroxypropyl p-phenylenediamine and its dihydrochloride salt are not safe when used in hair dyes.
The second question asks whether the “SCCS has any further scientific concerns regarding the use of Hydroxypropyl p-phenylenediamine and its dihydrochloride salt in cosmetic products.”
Contested use
The EC received a dossier from the industry in 2018 to support the safe use of Hydroxypropyl p-phenylenediamine and its dihydrochloride salt in hair dyes. As a result of consulting the SCCS, it concluded that “hydroxypropyl p-phenylenediamine and its dihydrochloride salt are not safe when used in oxidative hair coloring products due to potential genotoxicity.”
“The SCCS considers both the base and the salt form of hydroxypropyl p-phenylenediamine as in-vitro mutagens, and a mutagenic potential cannot be excluded,” outlined the organization in its 2019 opinion.
Moreover, The SCCS flagged that a “mild to moderate eye irritation potential of the test item cannot be excluded. Hydroxypropyl p-phenylenediamine 2HCl is a moderate skin sensitizer based on animal data.”
Previous analysis
In its previous examination, the SCCS carried out an in-vitro EpiskinSM skin irritation test – using a concentration of 2% in water – which was evaluated on three different batches of reconstructed human epidermis models. Based on this, it concluded that the concentration of 2% in water was considered potentially non-irritating.
Previously, SCCS also carried out a bovine corneal opacity and permeability test to check for eye irritation. 
The SCCS flagged that a mild to moderate eye irritation potential of the test item cannot be excluded.
“The in vitro evaluation of the acute ocular irritation potential of hydroxypropyl p-phenylenediamine HCl at a concentration of 2% in the bovine corneal opacity and permeability test suggested that this ingredient is slightly irritant for the isolated bovine cornea after 30 minutes and 4 hours of contact,” concluded the SCCS.
Moreover, it also tested skin sensitization using a local lymph node assay on mice. “Under the conditions of this study, hydroxypropyl p-phenylenediamine HCl did induce delayed contact hypersensitivity. According to the EC3 value (3.88%), hydroxypropyl p-phenylenediamine HCl was considered to have a moderate sensitizing potential,” stated the SCCS.
The dermal absorption study on frozen human dermatomed skin found that “hydroxypropyl p-phenylenediamine HCl present at a maximum final on-head concentration of 2% in a typical oxidative hair dye formulation penetrated through human dermatomed skin at a prolonged rate.”
In related news, the SCCS shared its final opinion on using the aglycone form of genistein and daidzein in cosmetics while factoring in its potential endocrine-disrupting properties. The compounds are currently used in cosmetics as antioxidants, skin protectants and skin and hair conditioning agents.
By Venya Patel
