Moderate Cosmetic Ingredient

CI 42051 (Patent Blue V / Acid Blue 3)

INCI: CI 42051

CAS Number
3536-49-0
Function
Colorant. Synthetic triphenylmethane blue dye (Patent Blue V, also known as Acid Blue 3, Food Blue 5, E131). Imparts blue coloration to cosmetic products. Water-soluble anionic sulfonated triphenylmethane dye used as a colorant in cosmetics, food (E131 in EU), and as a medical sentinel lymph node mapping agent. Available as calcium salt and insoluble barium, strontium, and zirconium lakes and pigments.
Safety Rating
MODERATE

Regulatory Status

🇪🇺 EU Status restricted
EU Max Conc. Permitted in non-hair-dye cosmetics under Annex IV (Entry IV/60); prohibited in hair dye formulations (Annex II Entry 1356). Applies to free acid, calcium salt, and insoluble lakes/pigments thereof.
🇺🇸 US Status prohibited
US Notes CI 42051 (Patent Blue V) is not listed on the FDA Color Additives Permitted for Use in Cosmetics (21 CFR Parts 73, 74, or 82). Patent Blue V has not been certified by FDA as a color additive for food, drugs, or cosmetics in the United States. Use in US cosmetics is not authorized. EWG VERIFIED program lists this ingredient as unacceptable for use in certified products.

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

Safety Data

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

Calculate MoS for your specific formulation with the MoS Calculator.

Expert Verdict

CI 42051 is permitted in EU non-hair-dye cosmetics under Annex IV but prohibited in hair dye formulations (Annex II). In the US, it is not FDA-authorized for cosmetic use. Rare hypersensitivity reactions documented in medical applications; contact sensitization from topical cosmetic use is infrequent. Regulatory authorization diverges significantly between EU and US markets.

⚠️
Concern Level: Moderate

Regulatory Flags

eu-annex-iv eu-hair-dye-prohibited-annex-ii not-fda-listed not-fda-approved-us ewg-unacceptable triphenylmethane-dye food-colorant-e131-eu medical-use-anaphylaxis-risk water-soluble calcium-salt-lakes-permitted eu_banned_cosmetics eu_children_restricted eu_cosing_listed jecfa_concern

Frequently Asked Questions

Is CI 42051 (Patent Blue V / Acid Blue 3) safe in cosmetics?

CI 42051 is permitted in EU non-hair-dye cosmetics under Annex IV but prohibited in hair dye formulations (Annex II). In the US, it is not FDA-authorized for cosmetic use. Rare hypersensitivity reactions documented in medical applications; contact sensitization from topical cosmetic use is infrequent. Regulatory authorization diverges significantly between EU and US markets. The EU classifies CI 42051 (Patent Blue V / Acid Blue 3) as "restricted". Safety rating: MODERATE.

Is CI 42051 (Patent Blue V / Acid Blue 3) allowed in the EU?

CI 42051 (Patent Blue V / Acid Blue 3) EU regulatory status: restricted. Maximum allowed concentration: Permitted in non-hair-dye cosmetics under Annex IV (Entry IV/60); prohibited in hair dye formulations (Annex II Entry 1356). Applies to free acid, calcium salt, and insoluble lakes/pigments thereof.. This is based on EU Regulation 1223/2009 and its amendments.

What does CI 42051 (Patent Blue V / Acid Blue 3) do in cosmetics?

CI 42051 (Patent Blue V / Acid Blue 3) functions as: Colorant. Synthetic triphenylmethane blue dye (Patent Blue V, also known as Acid Blue 3, Food Blue 5, E131). Imparts blue coloration to cosmetic products. Water-soluble anionic sulfonated triphenylmethane dye used as a colorant in cosmetics, food (E131 in EU), and as a medical sentinel lymph node mapping agent. Available as calcium salt and insoluble barium, strontium, and zirconium lakes and pigments.. It is classified as a cosmetic ingredient in our database. CAS number: 3536-49-0.

What is the Margin of Safety for CI 42051 (Patent Blue V / Acid Blue 3)?

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.

Compliance Tools

Check CI 42051 (Patent Blue V / Acid Blue 3) compliance across multiple jurisdictions:

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Ingredient Decoder
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82 Allergen Checker
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Substance Compliance
Check compliance across 55 jurisdictions
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MoS Calculator
Calculate Margin of Safety using SCCS methodology
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Heavy Metal Limits
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