Science
Mechanism of Action
As an azo dye, Solvent Red 23 functions by physically imparting color to formulations. Its primary mechanistic concern involves its metabolism in biological systems; within mammals, including human skin and gut microbiomes, it can undergo reductive cleavage. This process yields potentially carcinogenic metabolites such as 4-aminoazobenzene and aniline. Furthermore, studies in rat liver have indicated that CI 26100 can downregulate CYP4A protein expression and decrease mRNA expression of PPARα, a nuclear receptor involved in lipid and glucose homeostasis.
Research
Clinical Evidence
Low confidenceN/A
Transparency
Dusting Analysis
As an oil-soluble solvent dye rather than a particulate powder, Solvent Red 23 does not typically present a dusting risk during handling or formulation.
The Formula
Formulation
Stability
Solvent Red 23 is insoluble in water but readily dissolves in various organic solvents including benzene, chloroform, methanol, ethanol, acetone, and xylene. It demonstrates robust stability against heat, light, acids, and alkalis, suggesting compatibility across a wide pH range. The ingredient's melting point typically falls between 195°C and 201°C.
Conflicts
- strong oxidizing agents
Safety
Safety Profile
The Scientific Committee on Consumer Products (SCCS) in the EU concluded that the use of CI 26100 and similar azo dyes capable of releasing carcinogenic aromatic amines 'poses a risk to the health of the consumer'. Specifically, CI 26100 is noted to release 4-aminoazobenzene, which is classified as a Category 2 carcinogen in the EU. Its use in hair coloring products is prohibited within the EU. Health Canada has also identified Solvent Red 23 as potentially 'harmful to human health' and proposed its inclusion on their Cosmetic Ingredient Hotlist as a prohibited or restricted substance. While the FDA permanently lists D&C Red No. 17 (CI 26100) for use in drugs, cosmetics, and devices, it mandates certification and imposes restrictions for external application only in drugs and cosmetics, with specific limitations for contact lenses. The risk of absorption is elevated when applied to damaged skin, or areas such as the mouth, lips, or around the eyes. Solvent Red 23 is suspected to be an environmental toxin, persistent, and bioaccumulative, with some studies indicating weak endocrine disruption. Cases of contact dermatitis have been reported, particularly among hairdressers, potentially due to its hydrolysis into substances like p-phenylenediamine.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Given its potential to metabolize into carcinogenic aromatic amines, the EU prohibition in certain cosmetic categories, and Health Canada's proposed restrictions, Solvent Red 23 is an ingredient that should be avoided in all skincare formulations.
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