Science
Mechanism of Action
This ingredient operates as a preservative by gradually releasing formaldehyde within product formulations. This controlled release creates an antimicrobial environment, effectively preventing the proliferation of various microorganisms including Gram-positive and Gram-negative bacteria, yeast, and mold, thus safeguarding product integrity and extending its shelf life.
Research
Clinical Evidence
Medium confidence0.2%
Key findings
- 01 Demonstrates effective broad-spectrum antimicrobial activity, inhibiting bacterial, fungal, and mold growth at concentrations typically between 0.1% and 1.0%, thereby enhancing cosmetic product shelf life.
- 02 A study involving a 10mM (~0.127%) solution reported a significant cross-linking effect on porcine cornea, suggesting potential therapeutic tissue cross-linker applications, though not directly relevant to general skincare.
Transparency
Dusting Analysis
As a functional preservative, Sodium Hydroxymethylglycinate is typically included at concentrations effective for microbial inhibition, generally above 0.1%. It is not an ingredient commonly 'dusted' for skin benefits. However, its classification as a formaldehyde-releasing carcinogen by the EU and its potent sensitizing properties mean any concentration should be critically evaluated, with a theoretical releasable formaldehyde concentration of ≥ 0.1% w/w representing a significant safety red flag.
The Formula
Formulation
Stability
Exhibits stability across a broad pH range of 3 to 12. While generally stable at room temperature, exposure to high temperatures (preferably used below 80°C) or significant shifts in pH levels can accelerate the release of formaldehyde.
Conflicts
- Aldehyde-based essences (potential for reaction leading to colored substances)
- Citrus essential oils (may induce a pink coloration in the product)
Safety
Safety Profile
Sodium Hydroxymethylglycinate is a formaldehyde-releasing preservative with significant safety implications. Formaldehyde is classified as a known human carcinogen and a potent skin sensitizer. While the Cosmetic Ingredient Review (CIR) deems it safe for cosmetic use up to a maximum concentration of 0.5%, the European Union has listed it as a Category 1B carcinogen and has consequently prohibited its use in cosmetic products under REACH legislation. For very limited applications in rinse-off products, the maximum theoretical releasable formaldehyde concentration must not exceed 0.1% w/w. It poses a high risk for skin sensitization and irritation, potentially causing allergic contact dermatitis even at low concentrations.
Your Skin
Skin Compatibility
Our Assessment
Verdict
Despite its efficacy as a broad-spectrum preservative, the classification of Sodium Hydroxymethylglycinate as a formaldehyde-releasing carcinogen and potent sensitizer by the EU renders its use highly problematic and generally unsuitable for precision skincare formulations.
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References
Sources