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ACID GREEN 1.

Optional CAS 19381-50-1 / HAIR DYEING

Acid Green 1, also known as CI 10020, is a synthetic nitroso dye utilized primarily as a functional colorant in cosmetic formulations. It imparts a distinct yellow-green to dark-green hue to the product itself.

colorant

Science

This ingredient functions solely as a colorant by superfically tinting the product bulk. As an iron coordination complex, it lacks any biological mechanism of action or benefit on human skin tissue.


Research

Low confidence
Effective range 0.1–1%
Optimal

N/A

Key findings

  1. 01 Clinical studies confirm Acid Green 1's role as a colorant, with no evidence for direct skin health benefits.

Transparency

Not commonly dusted

The Formula

Solubility
Water
Optimal pH 7 – 9.5
0 7 14

Stability

The dye is stable in alkaline conditions (native pH ~9.3) but is highly photolabile and sensitive to long-term storage, which can cause fading. It shifts to brownish-yellow in acidic environments.

Conflicts

  • Strong oxidizing agents
  • Strong reducing agents
  • Strong acids (causes color shift to yellow/brown)
  • Light (UV exposure)

Safety

CIR Status
Safe as used
Max tested
1%
Sensitization risk Low

Formerly Ext. D&C Green No. 1, it's restricted in the U.S. but permitted in the EU and other regions as CI 10020 for rinse-off and non-mucosal products. Some jurisdictions prohibit its use in hair dyes.


Your Skin

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

Our Assessment

Optional

Acid Green 1 is a safe and well-tolerated cosmetic colorant, effectively providing visual appeal without contributing active benefits to skin health.


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References