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Moumoujus

BENZOPHENONE-4.

Valuable CAS 4065-45-6 / LIGHT STABILIZER, UV ABSORBER, UV FILTER

A versatile, water-soluble organic UV filter that serves a dual purpose: protecting the skin from short-wave radiation and maintaining the integrity of cosmetic formulations. By shielding light-sensitive ingredients, it prevents product discoloration and fragrance degradation over time.

Summary

UV Filter Light Stabilizer Sunscreen Active

Science

Mechanism of Action

Benzophenone-4 operates by absorbing UV energy, specifically targeting the UVB and short-wave UVA (UVA II) spectrum between 280–360 nm. Upon absorption, the molecule transitions to an excited state and subsequently releases the energy as harmless heat, returning to its stable ground state without losing its protective capacity.

Research

Clinical Evidence

High confidence
Effective range 0.1–10%
Optimal

5%

Key findings

  1. 01 A Kligman maximization test on 100 subjects confirmed no sensitization or irritation when tested at a 25% induction concentration.
  2. 02 A retrospective analysis of nearly 20,000 patients identified a 1.6% reaction rate, highlighting it as a low-level but emerging allergen.
  3. 03 Cumulative irritation testing on animal models showed minimal irritation scores (3.6%) even at the maximum 10% concentration.

Transparency

Dusting Analysis

Not commonly dusted
Min. effective
0.5%
Red flag below
0.1%

In skincare, this ingredient is often used at very low levels (under 0.5%) purely as a product stabilizer rather than a primary sunscreen active; while this isn't 'dusting' in a deceptive sense, it should not be mistaken for providing significant biological UV protection at such low doses.

The Formula

Formulation

Solubility
Water
Optimal pH 4 – 8
0 7 14

Stability

Inherently acidic (pH 1.2-2.2), requiring neutralization with bases like Sodium Hydroxide for stability. It is most effective near pH 5.5-6.0; exceeding pH 9.0 will cause a shift in its UV absorption spectrum.

Synergies

  • Oil-soluble UV filters
  • Antioxidants
  • Chelating agents

Conflicts

  • Magnesium salts
  • Cationic surfactants
  • Strong oxidizing agents

Safety

Safety Profile

CIR Status
Safe as used
Max tested
10%
Pregnancy
Safe
Sensitization risk Low

Global regulations vary: the FDA allows up to 10% as an OTC active (Sulisobenzone), while the EU SCCS limits cosmetic use to 5%.

Your Skin

Skin Compatibility

Yes Normal
Yes Dry
Yes Oily
No Sensitive
Irritancy Low
Comedogenicity Low

Our Assessment

Verdict

Valuable

An excellent secondary UV filter and stabilizer that ensures product longevity and provides supplemental protection against short-wave UVA and UVB radiation.

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