The pyrazole salt has been found to combine good stability as a raw material and good shade intensity with a range of common couplers when formulated in hair dyeing composition.
Submission I on the new hair dye was transmitted by Cosmetics Europe in May 2014 and after looking at all the scientific data provided, the SCCS came to its conclusion.
“The SCCS is of the opinion that 1-hexyl 4,5-diamine pyrazole sulfate is safe for use in oxidative hair dye formulations with an on-head concentration of maximum 1.0% taken into account the scientific data provided,” it says.
The committee does however note in its Opinion that the compound is a moderate skin sensitiser.
The ingredient is planned to be used as an oxidative hair colouring agent (precursor) in hair dye formulations at a maximum on-head concentration of 1.0%.
The oxidative dyeing of hair is one of the most extensively used methods to colour hair, in which precursors are used in combination with an oxidizing agent, commonly a peroxy oxidizing agent.
Tests and data
Looking at data and previous tests on the ingredient for corrosion and irritation, the SCCS notes that it is unlikely to have the potential to cause skin corrosion and that there is no requirement for it to be classified as an irritant either.
“Based on a TER assay and an EpiSkin test, 1 % 1-hexyl 4,5-diamine pyrazole sulfate is not considered to cause skin corrosion or skin irritation, respectively,” the SCCS notes.
The investigatory body does note that there is the potential for mild eye irritation of the ingredient but this is not classified as strong and is not of great concern; and under the experimental conditions it is also a moderate skin sensitiser.
“1-hexyl-1H-pyrazole-4,5-diamine hemisulfate is considered a moderate skin sensitiser according to the relative skin sensitisation potency classification scheme published in the ECETOC technical report on contact sensitisation,” says the Opinion.