Science
Mechanism of Action
Phenolsulfonphthalein operates as a highly sensitive pH indicator, undergoing reversible color changes determined by the surrounding acidity or alkalinity. It presents as yellow below pH 6.8, shifts to red within the neutral to slightly basic range of pH 6.8-8.2, and intensifies to fuchsia or deep pink when the pH exceeds 8.2. This characteristic property is precisely utilized to impart a specific color to cosmetic formulations.
Research
Clinical Evidence
Insufficient-data confidenceN/A
Transparency
Dusting Analysis
As a colorant, Phenolsulfonphthalein is not typically associated with 'dusting' concerns relevant to active ingredients for efficacy.
The Formula
Formulation
Stability
Phenolsulfonphthalein exhibits optimal color stability when formulated within a pH range of 3.0 to 7.0. It demonstrates heat tolerance; however, it is advised to maintain temperatures below 60°C during the mixing process in the water phase to preserve its color integrity, which is inherently pH-dependent.
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) Expert Panel has not conducted a dedicated safety assessment for Phenolsulfonphthalein. PubChem data indicates GHS hazard statements including H315 (Causes skin irritation), H319 (Causes serious eye irritation), and H335 (May cause respiratory irritation). Conversely, Environment Canada has classified it as not expected to be potentially toxic or harmful, nor persistent, bioaccumulative, or an environmental toxin. It is present in various personal care products.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Phenolsulfonphthalein serves as an optional cosmetic colorant, providing pH-dependent color; however, its safety has not been comprehensively reviewed by the CIR, and no specific skin benefits are established.
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References
Sources