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Moumoujus

ETHYL PABA.

Avoid CAS 94-09-7 / ORAL CARE, UV ABSORBER

Ethyl PABA, also known as Padimate O, is a chemical UV filter historically used to absorb UVB radiation. While effective at protecting against immediate sunburn, its safety profile is significantly compromised by evidence of increased mutagenicity upon sun exposure.

Summary

uv filter

Science

Mechanism of Action

As a chemical sunscreen agent, Ethyl PABA absorbs ultraviolet light in the UVB range (290-320 nm), peaking at 312 nm. This absorbed energy is converted into heat, preventing harmful UV rays from damaging skin cells. However, research indicates that light-modified Ethyl PABA can exhibit increased mutagenicity when exposed to sunlight, potentially causing DNA damage and contributing to the risk of sun-induced cancer.

Research

Clinical Evidence

Low confidence
Effective range 0.5–8%
Optimal

N/A

Key findings

  1. 01 Effective as a UVB filter, absorbing light in the 290-320 nm range.
  2. 02 A Margin of Safety (MOS) of 180.18 was calculated for sunscreen use at 8% concentration, deemed safe by Korea MFDS.
  3. 03 Studies highlight increased mutagenicity following sun exposure, suggesting a potential link to sun-induced cancer despite UVB protection.

Transparency

Dusting Analysis

Not commonly dusted

Ethyl PABA functions as a primary UV filter at active concentrations, typically between 0.5% and 8%. Its use is not associated with 'dusting' (inclusion at sub-efficacious levels for marketing claims). The primary red flag lies in its inherent safety concerns, specifically increased mutagenicity upon sun exposure, which raises serious questions about its overall suitability in skincare formulations at any effective concentration.

The Formula

Formulation

Solubility
Oil
Optimal pH N/A
0 7 14

Stability

Ethyl PABA is an oily liquid soluble in alcohol, strong acid, and strong base, but insoluble in water and acetic acid. Its derivative relationship to PABA suggests that the presence of free PABA could negatively impact formulation stability.

Conflicts

  • Sulfonamides (potential cross-sensitization)
  • Local anesthetics (potential cross-sensitization)
  • Azo dyes (potential cross-sensitization)
  • Paraphenylenediamine (potential cross-sensitization)
  • Aniline (potential cross-sensitization)

Safety

Safety Profile

CIR Status
Insufficient data
Max tested
8%
Sensitization risk Low

The US FDA regulates Ethyl PABA (Padimate O) at a maximum concentration of 8%. However, the European Union and Canada have banned PABA and its derivatives due to safety concerns. Animal studies indicate toxicity to the testis, epididymis, spleen, and liver. It has also been shown to inhibit cell growth and DNA synthesis in human keratinocytes at low concentrations. Caution is particularly advised for infants under six months due to a lack of understanding regarding its metabolism and absorption. The most significant concern is the confirmed increased mutagenicity upon sun exposure, potentially contributing to sun-induced cancer despite its UVB protective qualities.

Your Skin

Skin Compatibility

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

Our Assessment

Verdict

Avoid

Despite its historical use as a UVB filter, Ethyl PABA should be avoided in precision skincare formulations due to strong evidence of increased mutagenicity upon sun exposure and bans in major regulatory markets like the EU and Canada.

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