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SOLVENT RED 1.

Avoid CAS 1229-55-6 / HAIR DYEING

Solvent Red 1, also recognized as Sudan Red G, is a lipophilic azo dye historically employed for its red coloring properties. Its application in food products and many cosmetic formulations has been largely restricted or banned due to significant health and safety concerns.

Hair Dyeing Colorant

Science

This lipophilic azo dye achieves its coloring effect by dissolving directly into the substrate it is applied to, such as fats, oils, and waxes. Its primary and sole function is as a colorant, and it does not undergo ionization within a formulation.


Research

Low confidence
Effective range N/A
Optimal

N/A


Transparency

Not commonly dusted

Solvent Red 1 is a dye incorporated into formulations and is not typically encountered as a fine powder requiring dusting considerations for inhalation safety in cosmetic manufacturing.


The Formula

Solubility
Oil
Optimal pH N/A
0 7 14

Stability

Solvent Red 1 demonstrates good thermal stability, typically up to 100-110°C, with some sources reporting stability up to 180°C. However, its light fastness is considered poor, leading to potential color degradation upon light exposure. It exhibits moderate resistance to acids and alkalis, but exposure to strong acids can induce a deep red color change followed by dark red precipitation upon dilution, while strong alkalis may shift its color towards orange.

Conflicts

  • strong acids
  • strong alkalis

Safety

CIR Status
Not reviewed
Pregnancy
Caution
Sensitization risk Moderate

Solvent Red 1 is classified by ECHA as Carcinogen Category 1B, indicating a high probability that it 'may cause cancer' based on 92.5% of reports. It is a California Safe Cosmetics Program (CSCP) Reportable Ingredient due to concerns regarding bioaccumulation, environmental persistence, and its listing as a potential endocrine disrupting compound. Its use in many cosmetic applications and as a food dye has been largely restricted or banned in numerous countries due to these significant safety profiles and potential carcinogenic properties. The ingredient has been linked to causing contact dermatitis and general skin irritation, and studies suggest it possesses a weak contact sensitizing potential. Mutagenicity studies have presented conflicting results, with some suggesting weak mutagenic effects, potentially attributable to contaminants. EU Commission Regulation 2020/2081 specifies a maximum concentration limit of 0.1% by weight for Solvent Red 1 when used in tattoo inks and/or permanent makeup, underscoring regulatory caution for direct skin exposure in more invasive applications.


Your Skin

No Normal
No Dry
No Oily
No Sensitive
Irritancy Medium
Comedogenicity Unknown

Our Assessment

Avoid

Due to its classification as a Carcinogen Category 1B, documented association with skin irritation and sensitization, and widespread restrictions or bans in cosmetic applications, Solvent Red 1 is an ingredient that should be strictly avoided in skincare formulations.


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