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Moumoujus

POTASSIUM BORATE.

Avoid CAS 1332-77-0 / BUFFERING

Potassium Borate primarily functions as a buffering agent, helping to maintain the pH stability of cosmetic formulations. While historically used for mild antiseptic qualities, its contemporary application in skincare is under scrutiny due to evolving safety assessments.

Summary

Buffering Agent pH Adjuster Antioxidant (in vitro potential) Preservative (historical)

Science

Mechanism of Action

When introduced into an aqueous solution, Potassium Borate dissociates to form a mildly alkaline environment, exhibiting robust buffering capabilities. This mechanism allows it to neutralize acids and moderate strong alkalis, thereby stabilizing the product's pH.

Research

Clinical Evidence

Low confidence
Effective range 1.25–5%
Optimal

N/A

Key findings

  1. 01 Potassium tetraborate was observed to be non-genotoxic and enhanced total antioxidant capacity in cultured human blood cells at concentrations of 1.25, 2.5, and 5 µg/ml.

Transparency

Dusting Analysis

Not commonly dusted

No data available suggests potassium borate is commonly associated with dusting as a formulation issue within cosmetic applications. It is primarily a water-soluble buffering agent.

The Formula

Formulation

Solubility
Water
Optimal pH 7.5 – 9.2
0 7 14

Stability

Potassium Borate forms a mildly alkaline solution (a 2% solution has a pH of 9.2) and demonstrates excellent buffering properties. Its adsorption efficiency is highest under alkaline conditions, specifically between pH 7.5 and 9.0.

Conflicts

  • Strong oxidizing agents
  • Strong acids
  • Acid anhydrides
  • Strong reducing agents
  • Sodium salts (where sodium-free alkali borates are required)

Safety

Safety Profile

CIR Status
Safe with restrictions
Max tested
5%
Pregnancy
Caution
Sensitization risk Moderate

The CIR Expert Panel previously deemed Sodium Borate and Boric Acid (which Potassium Borate forms in water) safe at concentrations up to 5%, with explicit restrictions against use on infant or injured skin. However, the CIR assessment was re-opened in June 2024 to consider new data and potential EU regulatory bans. The SCCS states that potassium borate, upon contact with water, breaks down into boric acid, which is classified as a CMR (Carcinogenic, Mutagenic, or Reprotoxic) category 1B substance, strongly implying a potential prohibition for cosmetic use in the EU. Health Canada's Hotlist also restricts its use to 5% maximum in topical natural health products, advising against application on broken or abraded skin for children over 3. Furthermore, OSHA classifies Potassium Tetraborate as 'Suspected of damaging the unborn child' (Reproductive Toxicity, Category 2).

Your Skin

Skin Compatibility

No Normal
No Dry
No Oily
No Sensitive
Irritancy Unknown
Comedogenicity Unknown

Our Assessment

Verdict

Avoid

Potassium Borate is not recommended for Moumoujus formulations due to significant safety concerns, including its classification as a CMR 1B substance by the SCCS upon forming boric acid, warnings regarding reproductive toxicity, and ongoing re-evaluation by regulatory bodies globally, which may lead to prohibitions.

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