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ACID BLUE 1.

Optional CAS 129-17-9 / HAIR DYEING

Acid Blue 1 is a synthetic triarylmethane colorant that imparts a brilliant blue or greenish-blue hue to formulations, widely approved for use across various cosmetic categories.

colorant

Science

This colorant functions by absorbing specific light wavelengths, notably around 630-640 nm. In hair dyes, it adheres to the hair shaft surface via electrostatic interactions, acting as a non-oxidative direct coloring agent.


Research

Low confidence
Effective range N/A
Optimal

N/A

Key findings

  1. 01 Dietary NOAEL (No Observed Adverse Effect Level) established at 1-2% in a 104-week carcinogenicity/toxicity study.
  2. 02 Oral challenge tests showed hypersensitivity reactions in 1-14% of sensitive individuals with asthma/urticaria (not directly relevant to topical application).

Transparency

Not commonly dusted

The Formula

Solubility
Water
Optimal pH 3 – 8
0 7 14

Stability

Highly water-soluble and stable under normal storage and heat. It exhibits fair light fastness and poor oxidation fastness. Above pH 3.0, it appears deep blue, turning yellow-orange below pH 0.8.

Conflicts

  • Strong oxidizing agents
  • Manganese dioxide
  • Persulfates
  • Certain metal ions (Copper/Iron can cause a dark green discoloration)

Safety

CIR Status
Safe as used
Max tested
GMP%
Sensitization risk Low

The FDA permanently lists Acid Blue 1 as safe for foods, drugs, and cosmetics, including the eye area (21 CFR 74.101, 74.1101, 74.2101). In the EU, it is permitted in all cosmetics without specific concentration limits, provided purity standards are met.


Your Skin

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Optional

A widely approved and well-tolerated synthetic blue colorant, providing aesthetic value without offering direct skin benefits.


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