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BASIC BLUE 7.

Avoid CAS 2390-60-5 / HAIR DYEING

A synthetic cationic triarylmethane dye primarily utilized for its intense pigmenting properties in hair and nail applications. Due to its specific chemical structure, it acts as a direct colorant that interacts with negatively charged biological surfaces via electrostatic attraction.

colorant

Science

As a cationic dye, Basic Blue 7 binds strongly to anionic substrates like keratin fibers. Beyond its coloring capabilities, it serves as a photosensitizer; when exposed to light at approximately 600 nm, it triggers photodynamic reactions that can lead to significant cellular toxicity.


Research

Low confidence
Effective range 5e-8–0.002%
Optimal

0.2%

Key findings

  1. 01 Observed photodynamic cytotoxicity in human leukemic cell lines (K-562/TF-1), reaching 75% cell death at 5 x 10^-8 M concentration under 600 nm light.
  2. 02 Achieved over 99% cell lethality in human leukemic models at a concentration of 1 x 10^-7 M upon exposure to visible light.
  3. 03 Historically utilized at 0.2% in hair tinting, though modern safety evaluations have led to widespread regulatory restrictions.

Transparency

Not commonly dusted
Min. effective
0.01%
Red flag below
0.2%

While it may be included at low concentrations for visual aesthetics in hair products, its presence in leave-on skincare is a red flag due to cytotoxicity concerns and lack of approval for skin contact.


The Formula

Solubility
Water
Optimal pH 3 – 9
0 7 14

Stability

Highly sensitive to pH extremes; it shifts to brownish-yellow below pH 1 and reddish-brown above pH 12. Most stable in neutral to slightly acidic environments.

Conflicts

  • Anionic surfactants (e.g., Sodium Lauryl Sulfate)
  • Strong oxidizing agents
  • Sodium Hydroxide

Safety

CIR Status
Insufficient data
Max tested
0.2%
Pregnancy
Caution
Sensitization risk Moderate

Listed under EU Annex II as a prohibited substance. It is banned in California (effective 2027) and lacks FDA approval for use in any cosmetics intended for skin contact.


Your Skin

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

Our Assessment

Avoid

Basic Blue 7 presents significant safety concerns, including phototoxicity and regulatory prohibitions, making it unsuitable for precision skincare.


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References