EU SCCS seeks feedback on hair dye chemicals hydroxypropyl p-phenylenediamine and its dihydrochloride salt

On November 7, 2023, the European Union's Scientific Committee on Consumer Safety (SCCS) released a preliminary opinion on the use of hydroxypropyl p-phenylenediamine and its dihydrochloride salt in oxidative hair colourants. Hair colouring cosmetic products contain hydroxypropyl p-phenylenediamine and its dihydrochloride salt. They are currently not covered by the Cosmetics Regulation.

About the SCCS opinion

A dossier in favour of the safe use of hydroxypropyl p-phenylenediamine (CAS No. 73793-79-0) and its dihydrochloride salt (CAS No. 1928659-47-5) in cosmetic products was received by the Commission Services in 2018. However, because of the possibility of genotoxicity, the SCCS concluded that the substances should not be used in oxidative hair colouring products. The applicant submitted a second dossier in June 2022, requesting a re-assessment of the safety of p-phenylenediamine and its dihydrochloride salt for use in oxidative hair colouring products up to a concentration of 2% on-head.

Conclusion of the SCCS

Based on the information presented, the SCCS concludes that hydroxypropyl p-phenylenediamine and its dihydrochloride salt are safe when used in oxidative hair colouring products at a maximum concentration of 2% on-head. The possibility that the test substance may cause mild to moderate eye discomfort cannot be ruled out. According to animal studies, hydroxypropyl p-phenylenediamine and its dihydrochloride salt cause moderate cutaneous sensitization.

The opinion is open for public comment until January 8, 2024.