Science
Mechanism of Action
This ingredient functions as a multi-faceted agent within cosmetic systems. As a chelating agent, it binds to metal ions, preventing them from destabilizing formulations and thus extending product shelf-life and efficacy. It further contributes as an emulsifier and stabilizer, promoting homogeneous textures and preventing ingredient separation. Additionally, it helps regulate the product's pH, which can support the skin's natural barrier function and improve the absorption and activity of other beneficial ingredients.
Research
Clinical Evidence
Low confidence0.1%
Key findings
- 01 At a 1% concentration, Sodium Metaphosphate was found to be mildly irritating to the skin of human subjects in some safety assessments.
- 02 At a 1% concentration, Sodium Metaphosphate (and related polyphosphates) produced no irritation in contact allergy patients, indicating general tolerability in a sensitive population.
Transparency
Dusting Analysis
Formulation considerations highlight 'dust generation' as a potential issue, indicating that this ingredient can create dust, which should be managed during handling.
The Formula
Formulation
Stability
Sodium Metaphosphate is stable in dry conditions. Its aqueous solution typically exhibits a pH between 5.8 and 7.3, but can be acidic and hydrolyze into phosphite over time. It is important to distinguish that while the general term 'Sodium Metaphosphate' may include practically insoluble long-chain forms, its common cosmetic derivatives like Sodium Hexametaphosphate and Sodium Trimetaphosphate are soluble in water.
Conflicts
- incompatible materials
- excess heat
- strong acids
- strong bases
- pH mismatch with ingredients requiring different pH ranges for stability or efficacy
Safety
Safety Profile
The Cosmetic Ingredient Review (CIR) panel has determined Sodium Metaphosphate (and related polyphosphates) to be safe for cosmetic use when formulated to be non-irritating. Concentrations typically range from 0.01% to 9.6%, with higher levels in rinse-off products. In leave-on topical products, its use as a chelator is generally below 0.1%. Safety relies on appropriate formulation to avoid skin irritation, such as utilizing low concentrations in leave-on products or ensuring proper dilution.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Sodium Metaphosphate is a valuable formulation aid, crucial for maintaining product stability, texture, and pH balance, thereby indirectly supporting skin health with a generally low irritancy profile when properly formulated.
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