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CHLOROBUTANOL.

Questionable CAS 57-15-8 / PRESERVATIVE

Chlorobutanol is an alcohol-based preservative with broad-spectrum antimicrobial activity against various bacteria, fungi, and some viruses. It is utilized for long-term stability in multi-ingredient formulations.

Preservative Antimicrobial/antibacterial

Science

Primarily bacteriostatic, chlorobutanol exerts its antimicrobial action by disrupting microbial cell membranes, thereby inhibiting growth. It also possesses mild local anesthetic properties upon topical application.


Research

Medium confidence
Effective range 0.05–0.5%
Optimal

N/A

Key findings

  1. 01 Antimicrobial activity in water is observed from 0.05%.
  2. 02 Minimum inhibitory concentrations range from 0.065% (Gram-positive bacteria) to 0.5% (fungi).
  3. 03 However, 0.5% concentration has caused significant corneal damage and irritation in over 50% of subjects in studies.

Transparency

Not commonly dusted

The Formula

Solubility
Both
Optimal pH ≤5.5
0 7 14

Stability

Chlorobutanol is volatile, subliming readily, and degrades in aqueous solutions, with optimal stability at pH 3. Antimicrobial activity is significantly reduced above pH 5.5, and 0.5% solutions may crystallize at lower temperatures.

Conflicts

  • Plastic vials (sorption)
  • Rubber stoppers (sorption)
  • Bentonite (sorption)
  • Magnesium trisilicate (sorption)
  • Polyethylene (sorption)
  • Polyhydroxyethylmethacrylate (sorption)
  • Carboxymethylcellulose (reduced activity)
  • Polysorbate 80 (reduced activity)

Safety

CIR Status
Insufficient data
Max tested
0.5%
Sensitization risk Low

The FDA and UK permit up to 0.5% in cosmetics, but it is generally described as an irritant at this concentration. The EMA notes systemic exposure exceeding 0.5 mg/day for long-term use raises concerns for cardiovascular and reproductive toxicity.


Your Skin

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

Our Assessment

Questionable

While effective as a broad-spectrum preservative at low concentrations, its significant irritation potential at higher functional levels and complex formulation considerations make it a questionable choice for precision skincare.


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