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BENZIMIDAZOLE.

Valuable CAS 51-17-2 / NOT REPORTED

Commonly known in its neutralized form as Ensulizole, this water-soluble chemical filter provides robust protection against UVB radiation. Its unique ability to create lightweight, non-greasy finishes makes it a staple in high-performance, breathable sun care formulations.

UVB Filter Photo-protective Agent

Science

It acts as a chemical UV absorber that targets the UVB spectrum (290–320 nm), reaching peak efficiency at 310 nm. Upon exposure, it intercepts high-energy photons and converts them into harmless thermal energy, effectively preventing DNA damage and solar erythema.


Research

High confidence
Effective range 1–8%
Optimal

4%

Key findings

  1. 01 Clinical evaluation at 8% concentration confirmed minimal dermal absorption (0.259%), ensuring the ingredient remains on the skin surface with negligible systemic presence.
  2. 02 In vitro analysis at 4mM demonstrated a significant reduction in cyclobutane pyrimidine dimers (CPDs), protecting cellular integrity against UVB-induced mutations.

Transparency

Not commonly dusted
Min. effective
1%
Red flag below
0.5%

As a regulated active sunscreen agent, it is rarely 'dusted' because specific concentration levels are required to achieve and claim a measured SPF rating. Using it below 1% would generally serve no functional protective purpose.


The Formula

Solubility
Water
Optimal pH 6.8 – 7.2
0 7 14

Stability

Requires precise neutralization with alkaline agents like Sodium Hydroxide to maintain solubility; if the formulation pH drops below 6.8, the ingredient will crystallize and precipitate.

Synergies

  • Avobenzone
  • Water-soluble antioxidants
  • Humectants

Conflicts

  • High-concentration Carbomers
  • Highly acidic actives (L-Ascorbic Acid)
  • Specific waterproofing polymers

Safety

CIR Status
Safe as used
Max tested
8%
Pregnancy
Safe
Sensitization risk Low

While the EU permits up to 8%, regions including the US, Canada, and Australia cap usage at 4%. It is widely recognized for its excellent safety profile and lack of phototoxic potential.


Your Skin

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Valuable

An essential UV filter for achieving high-SPF protection in elegant, water-based textures without the heaviness of traditional oils.


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