Moderate Active Ingredient NOAEL Data

Ensulizole

INCI: PHENYLBENZIMIDAZOLE SULFONIC ACID

CAS Number
27503-81-7
Function
Water-soluble UVB UV filter; peak absorption ~310 nm; unique sulfonic acid moiety confers water-solubility — enables use in lightweight aqueous formulations; preferred for facial moisturizers, primers, and fluids requiring non-greasy SPF
Safety Rating
MODERATE

Regulatory Status

🇪🇺 EU Status permitted
EU Max Conc. 4%
🇺🇸 US Status restricted
US Notes Historically marketed in the US; FDA states existing data is not sufficient to determine GRASE. Regulatory limbo alongside seven other chemical filters. Final determination pending additional safety data.

For full compliance data across 55 jurisdictions, use the Substance Compliance tool.

Safety Data

Margin of Safety (MoS)
not established
Dermal Absorption
moderate
Sensitization
low

Calculate MoS for your specific formulation with the MoS Calculator.

Toxicological Studies

2 study endpoints found for Ensulizole. NOAEL (No Observed Adverse Effect Level) values are used to calculate the Margin of Safety per SCCS methodology.

Endpoint Value Route Species Study Type Source
NOAEL 1000 mg/kg bw/day oral rat Subchronic COSMOS_DB
NOAEL 1000 mg/kg bw/day oral rat oral REACH

Expert Verdict

Water-soluble UVB filter uniquely positioned for lightweight daily SPF formulations due to its polar sulfonic acid moiety. Non-greasy, clear-finish aesthetic makes it the preferred UV filter in facial moisturizers with SPF and cosmetic-adjacent products. FDA limbo due to systemic absorption detection in PK studies, not specific toxicity findings. EU-permitted at ≤4%. No significant endocrine or reef-toxicity profile relative to high-concern filters. Always requires co-formulation with a UVA filter for broad-spectrum compliance — UVB-only coverage is the primary limitation.

⚠️
Concern Level: Moderate

Regulatory Flags

uv-filter uvb water-soluble sulfonic-acid fda-limbo systemic-absorption lightweight daily-spf non-greasy aqueous-phase low-concern-relative-to-class ifra_fragrance eu_cosing_listed

Frequently Asked Questions

Is Ensulizole safe in cosmetics?

Water-soluble UVB filter uniquely positioned for lightweight daily SPF formulations due to its polar sulfonic acid moiety. Non-greasy, clear-finish aesthetic makes it the preferred UV filter in facial moisturizers with SPF and cosmetic-adjacent products. FDA limbo due to systemic absorption detection in PK studies, not specific toxicity findings. EU-permitted at ≤4%. No significant endocrine or reef-toxicity profile relative to high-concern filters. Always requires co-formulation with a UVA filter for broad-spectrum compliance — UVB-only coverage is the primary limitation. The EU classifies Ensulizole as "permitted". Safety rating: MODERATE. 2 toxicological study endpoint(s) are available in our database.

Is Ensulizole allowed in the EU?

Ensulizole EU regulatory status: permitted. Maximum allowed concentration: 4%. This is based on EU Regulation 1223/2009 and its amendments.

What does Ensulizole do in cosmetics?

Ensulizole functions as: Water-soluble UVB UV filter; peak absorption ~310 nm; unique sulfonic acid moiety confers water-solubility — enables use in lightweight aqueous formulations; preferred for facial moisturizers, primers, and fluids requiring non-greasy SPF. It is classified as a Active Ingredient in our database. CAS number: 27503-81-7.

What is the Margin of Safety for Ensulizole?

not established The Margin of Safety (MoS) is calculated using SCCS methodology. A MoS above 100 is generally considered safe. Use the MoS Calculator tool to calculate MoS for your specific formulation and product category.

What is the NOAEL for Ensulizole?

The NOAEL (No Observed Adverse Effect Level) for Ensulizole is 1000 mg/kg bw/day based on a Subchronic study via oral route in rat. A total of 2 study endpoints are available. Source: COSMOS_DB.

📱

Is Ensulizole in Your Products?

Scan any product label with Piro — our free ingredient scanner. Point your camera at the ingredients list and get instant safety scores for every ingredient.

Try Piro Free →

Analyze Your Full Ingredient List

Paste any INCI list into the Decoder for instant safety analysis, or calculate the Margin of Safety for Ensulizole in your formulation.