Moderate Cosmetic Ingredient

CI 42045 (Acid Blue 1 / D&C Blue No. 4)

INCI: CI 42045

CAS Number
129-17-9
Function
Colorant. Synthetic triphenylmethane blue dye (Acid Blue 1, also known as D&C Blue No. 4, Food Blue 2). Imparts blue coloration to cosmetic and personal care products. Water-soluble anionic sulfonated triphenylmethane dye. Approved for limited cosmetic use under EU and US regulations, with key restrictions preventing use in hair dye products and limiting scope to non-mucosal applications.
Safety Rating
MODERATE

Regulatory Status

🇪🇺 EU Status restricted
EU Max Conc. No maximum concentration specified for permitted applications. Prohibited in hair dye products (Annex II/1355). Prohibited in products applied to mucous membranes (Annex IV restriction). Purity per EU standards required.
🇺🇸 US Status permitted
US Notes FDA permanently listed as D&C Blue No. 4 (21 CFR 74.2104). Subject to mandatory FDA batch certification before US market distribution. Approved for externally applied cosmetics only. NOT permitted for use in the eye area, ingested products, injections, or surgical sutures per 21 CFR 74.2104 restrictions. External use only with batch certification required.

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

Safety Data

Margin of Safety (MoS)
adequate
Dermal Absorption
low
Sensitization
low

Calculate MoS for your specific formulation with the MoS Calculator.

Expert Verdict

CI 42045 (Acid Blue 1 / D&C Blue No. 4) is a sulfonated triphenylmethane dye with restricted EU status and permitted US status. EU regulations prohibit use on mucous membranes and entirely in hair dye products, while FDA limits it to externally applied cosmetics with batch certification, excluding the eye area and mucosal applications. Moderate concern reflects applicability restrictions across both regulatory frameworks.

⚠️
Concern Level: Moderate

Regulatory Flags

eu-annex-iv eu-mucous-membrane-prohibited eu-hair-dye-prohibited-annex-ii fda-d-and-c-blue-no-4 fda-batch-certification-required external-use-only-us no-eye-area-us triphenylmethane-dye water-soluble sulfonated eu_banned_cosmetics eu_cosing_listed

Frequently Asked Questions

Is CI 42045 (Acid Blue 1 / D&C Blue No. 4) safe in cosmetics?

CI 42045 (Acid Blue 1 / D&C Blue No. 4) is a sulfonated triphenylmethane dye with restricted EU status and permitted US status. EU regulations prohibit use on mucous membranes and entirely in hair dye products, while FDA limits it to externally applied cosmetics with batch certification, excluding the eye area and mucosal applications. Moderate concern reflects applicability restrictions across both regulatory frameworks. The EU classifies CI 42045 (Acid Blue 1 / D&C Blue No. 4) as "restricted". Safety rating: MODERATE.

Is CI 42045 (Acid Blue 1 / D&C Blue No. 4) allowed in the EU?

CI 42045 (Acid Blue 1 / D&C Blue No. 4) EU regulatory status: restricted. Maximum allowed concentration: No maximum concentration specified for permitted applications. Prohibited in hair dye products (Annex II/1355). Prohibited in products applied to mucous membranes (Annex IV restriction). Purity per EU standards required.. This is based on EU Regulation 1223/2009 and its amendments.

What does CI 42045 (Acid Blue 1 / D&C Blue No. 4) do in cosmetics?

CI 42045 (Acid Blue 1 / D&C Blue No. 4) functions as: Colorant. Synthetic triphenylmethane blue dye (Acid Blue 1, also known as D&C Blue No. 4, Food Blue 2). Imparts blue coloration to cosmetic and personal care products. Water-soluble anionic sulfonated triphenylmethane dye. Approved for limited cosmetic use under EU and US regulations, with key restrictions preventing use in hair dye products and limiting scope to non-mucosal applications.. It is classified as a cosmetic ingredient in our database. CAS number: 129-17-9.

What is the Margin of Safety for CI 42045 (Acid Blue 1 / D&C Blue No. 4)?

adequate 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.

Compliance Tools

Check CI 42045 (Acid Blue 1 / D&C Blue No. 4) compliance across multiple jurisdictions:

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Ingredient Decoder
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82 Allergen Checker
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Substance Compliance
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MoS Calculator
Calculate Margin of Safety using SCCS methodology
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Heavy Metal Limits
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