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PHENYL MERCURIC BENZOATE.

Avoid CAS 94-43-9 / PRESERVATIVE

Phenyl Mercuric Benzoate is an organic aryl mercury compound that has historically been utilized as a preservative to prevent microbial proliferation in formulations. Its lipophilic nature enables it to cross biological barriers, facilitating absorption.

preservative

Science

This compound primarily functions as a preservative by inhibiting the growth of a wide spectrum of microorganisms. As an organic aryl mercury derivative, its lipophilic properties allow it to penetrate and traverse biological membranes, including the skin.


Research

Low confidence
Effective range N/A
Optimal

N/A


Transparency

Not commonly dusted

The provided research does not contain information related to 'dusting' claims or thresholds for this ingredient.


The Formula

Solubility
Both
Optimal pH N/A
0 7 14

Stability

Phenyl Mercuric Benzoate exhibits sparing solubility in water (estimated at 30.96 mg/L at 25°C) but is also lipophilic. A related compound, phenylmercuric nitrate, demonstrated significant degradation (to mercuric ion and benzene) during heat sterilization (121°C for 15 minutes) in the presence of disodium edetate, particularly at lower pH values (100% degradation at pH 5 and 6, 80% at pH 7, 15% at pH 8). It is generally incompatible with strong oxidizing agents, strong acids, and strong bases.

Conflicts

  • strong oxidizing agents
  • strong acids
  • strong bases
  • disodium edetate (under heat sterilization)

Safety

CIR Status
Not reviewed
Max tested
0.007%
Pregnancy
Caution
Sensitization risk High

The Scientific Committee on Consumer Safety (SCCS) of the European Union issued a preliminary opinion in October 2025, concluding that phenylmercuric salts, including benzoate, cannot be considered safe at currently permitted concentrations in cosmetic products due to concerns over renal toxicity, unclear genotoxicity, and cumulative mercury exposure. EU Regulation (EC) No. 1223/2009 generally prohibits mercury compounds in cosmetics, with specific, narrow exceptions for eye products at a maximum of 0.007% (expressed as mercury) only if no other safe and effective preservative is available, requiring a 'Contains Phenylmercuric compounds' warning. Similarly, the U.S. FDA banned mercury in most cosmetics decades ago, with a limited exception for mascara up to 0.0065% (65 ppm) under the condition of no safer alternative. Mercury compounds are readily absorbed through the skin, accumulate in the body, and are associated with allergic reactions, skin irritation, and neurotoxic effects. Australia classifies this ingredient as hazardous with the risk phrase 'Danger of cumulative effects'.


Your Skin

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

Our Assessment

Avoid

Given significant regulatory prohibitions and severe safety warnings from major health authorities regarding its toxicity, bioaccumulation, and high irritancy potential, Phenyl Mercuric Benzoate should be avoided in skincare formulations.


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