On November 7, 2023, EU Scientific Committee on Consumer Safety (SCCS) published the preliminary opinion on the use of Hydroxypropyl p-Phenylenediamine (CAS No. 73793-79-0) and its dihydrochloride salt (CAS No. 1928659-47-5) in oxidative hair colouring products. The opinion is open for comments until January 8, 2024.1
Hydroxypropyl p-Phenylenediamine and its dihydrochloride salt are commonly used as hair dyes. In 2018, the industry submitted a dossier to support their safe use in cosmetics. Based on this dossier, SCCS released the opinion SCCS/1608/19, concluding that these substances were not safe when used in oxidative hair colouring products due to potential genotoxicity. Besides, SCCS indicated that a mild to moderate potential for eye irritation from the test items could not be ruled out.
In June 2022, the industry provided additional data addressing the issue of genotoxicity to SCCS. In response, the latter conducted another safety assessment and prepared this preliminary opinion. In light of the data provided, SCCS considers Hydroxypropyl p-Phenylenediamine and its dihydrochloride salt safe for use in oxidative hair colouring products up to an on-head concentration of 2%. However, SCCS reiterates its concerns over the potential for eye irritation from the test items.