Science
Mechanism of Action
On the skin, CI 42051 functions solely as an external cosmetic colorant. It provides a visual dark bluish or greenish-blue hue to formulations, with its appearance dynamically shifting based on the pH environment of the product.
Research
Clinical Evidence
High confidenceN/A
Transparency
Dusting Analysis
The Formula
Formulation
Stability
CI 42051 exhibits robust thermal stability, enduring temperatures up to at least 255 °C and maintaining integrity under standard ambient conditions. Its color is profoundly pH-dependent, presenting as deep blue in alkaline or weakly acidic formulations (pH 2.0-11.0) and transitioning to yellow-orange under stronger acidic conditions (pH 0.8-3.0). It is crucial to note its susceptibility to light-induced fading; incorporating a UV filter in the formulation is recommended to preserve color vibrancy.
Conflicts
- Strong oxidizers
- Direct light irradiation
- Humidity
Safety
Safety Profile
CI 42051 is regulated in Europe under specific restrictions (IV/60, II/1356) and must adhere to purity criteria for E 131. In the USA, the FDA permits a maximum concentration of 5.00% in skincare. While safety data sheets classify it as not acutely toxic, non-corrosive/irritant to skin or eyes, and not a respiratory or skin sensitizer according to Regulation (EC) No 1272/2008 (CLP), it is not advised for use in products intended for children in Australia and the US due to reported potential for allergic reactions, nausea, itching, and, in rare instances, anaphylactic shock in this demographic. It is not identified as a PBT or vPvB substance.
Your Skin
Skin Compatibility
Our Assessment
Verdict
CI 42051 is an optional cosmetic colorant providing a pH-sensitive blue hue, suitable for most skin types with careful consideration for light stability and specific populations.
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