Hair dye 1,2,4-trihydroxybenzene (1,2,4-THB) - A33 (CAS 533-73-3) - Submission VI

WG on Cosmetic Ingredients
SCCS members: U. Bernauer, L. Bodin, Q. Chaudhry, P.J. Coenraads (Chairperson), M. Dusinska, J. Ezendam, E. Gaffet, C. L. Galli, B. Granum, E. Panteri, V. Rogiers, Ch. Rousselle, M. Stepnik (Rapporteur), T. Vanhaecke, S. Wijnhoven
SCCS external experts: A. Koutsodimou, A. Simonnard, W. Uter
Contact: SANTE-C2-SCCSec [dot] europa [dot] eu (SANTE-C2-SCCS[at]ec[dot]europa[dot]eu)
On request from: European Commission
SCCS Number: SCCS/1598/18
Adopted on: 20-21 June 2019

Conclusion of the opinion:

1. In light of the data provided, does the SCCS consider 1,2,4-trihydroxybenzene (1,2,4-THB) (A33) safe for use as an auto-oxidative hair dye in permanent hair dye formulations, not requiring the action of peroxide, with a maximum on-head concentration of 2.5%?

On the basis of all the data submitted by the Applicant, and the data available in open literature, the SCCS does not consider 1,2,4-trihydroxybenzene safe due to potential genotoxicity when used as an auto-oxidative hair dye component in permanent hair dye formulations.

The data provided by the Applicant indicate that consumers would be exposed to unreacted 1,2,4-THB and (semi)quinones during the use of a 1,2,4-THB containing hair dye formulation. The systemic availability of 1,2,4-THB raises the risk of intracellular generation of hydrogen peroxide, as well as potential genotoxicity via DNA adduct formation by 1,2,4-THB and/or (semi)quinones. These aspects have not been addressed in the studies provided in the submission.

2. In light of the data provided, does the SCCS consider 1,2,4-trihydroxybenzene (1,2,4-THB) (A33) safe for use as an auto-oxidative hair dye in hair colour shampoo formulations, not requiring the action of peroxide, with a maximum on-head concentration of 0.7%?

See above.

3. Does the SCCS have any further scientific concerns with regard to the use of 1,2,4-trihydroxybenzene (1,2,4-THB) (A33) in cosmetic products?

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Keywords:

SCCS, scientific opinion, 1,2,4-trihydroxybenzene (1,2,4-THB), A33, hair dye, CAS: 533-73-3, EC 208-575-1, SCCS/1598/18, Regulation 1223/2009

Opinion to be cited as:

SCCS (Scientific Committee on Consumer Safety), Opinion 1,2,4-trihydroxybenzene (1,2,4-THB) - A33 – Submission VI, preliminary version of 21-22 June 2018, final version of 20-21 June 2019, SCCS/1598/18.