[Updated] EU SCCS Finalizes the Opinion About Hydroxypropyl p-Phenylenediamine and Its Dihydrochloride Salt

Editor's note: This article was originally published on November 7, 2023, and was updated on March 6, 2024, as per the latest developments. The updated contents are marked in red below.

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. Following the consultation period, SCCS released the final opinion on March 5, 2024, which reaffirms the same conclusion.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.

Further Reading

• EU REACH to Restrict Intentionally-added Microplastics in Cosmetics

• Exploring EU's Animal Testing: From Bans to Regulatory Interfaces and Beyond