What is E180?

Complete guide to understanding E180 (Lithol Rubine BK) – the synthetic red azo dye for cheese coating

The Quick Answer

E180 is Lithol Rubine BK (also called Pigment Red 57:1, Litholrubine)—a synthetic red azo dye derived from petroleum that is approved only for coating cheese rinds, where it is not typically ingested. It’s a calcium salt of a mono-azo compound containing a sulfonated naphthoic acid core structure. E180 is a bright bluish-red pigment used to color the exterior coating of certain cheeses (primarily red cheddar, mimolette, edam, gouda).

Unlike most synthetic food dyes that color the interior of foods, E180 has an unusual regulatory status: it is approved in the European Union but with the specific stipulation that it is used ONLY for surface coating of cheese. This is because E180 is a pigment—insoluble in water and only slightly soluble in hot water—making it unsuitable for use in most foods where color penetration is needed. The dye essentially remains on the cheese surface and is not typically ingested.

E180 is EU-authorized with an Acceptable Daily Intake (ADI) of 1.5 mg/kg body weight. However, since it’s used only for external cheese coating and not intended to be ingested, actual dietary exposure is minimal to negligible. It is BANNED in the United States and several other countries, reflecting safety concerns about this particular azo dye.

What Exactly Is It?

E180 is a synthetic mono-azo pigment (not a soluble dye) composed of calcium salt of a sulfonated naphthoic acid azo compound derived from petroleum through multi-step organic chemistry. It’s a bright red pigment used industrially in inks, paints, and coatings, and approved in the EU only for coating cheese rinds.

Think of E180 as an industrial pigment—the same compound used to produce red inks and paints. Unlike soluble dyes that dissolve in foods and color them throughout, E180 is a water-insoluble pigment that sits on the surface of cheese, providing color without penetrating. This property—being insoluble—is why its food application is so limited compared to other food dyes.

Key characteristic: E180 is a pigment, not a dye. This is critical to understanding its regulatory status. Because it doesn’t dissolve in water or food, it remains on the cheese surface and is minimally ingested. This different mechanism of action (surface coating only) distinguishes E180 from most other approved food colorants that actually color the food interior.

Chemical identity:

• Chemical class: Mono-azo dye (contains one azo linkage: -N=N-)
• Full chemical name: Calcium 3-hydroxy-4-[(4-methyl-2-sulphonatophenyl)azo]-2-naphthoate
• Molecular formula: C₁₈H₁₂CaN₂O₆S
• Core structure: Naphthoic acid (two fused benzene rings) with azo linkage to sulfonated benzene ring
• Azo linkage: One -N=N- bond; chromophore responsible for red color
• Sulfonate group: SO₃⁻ on phenyl ring providing some hydrophilicity (though still predominantly hydrophobic)
• Calcium salt: Disodium or calcium salt form; calcium form used in food (Ca²⁺ counter-ion)

How it’s made:

E180 is produced through petroleum-based synthetic chemistry:

• Starting materials: Aromatic amines (methylaniline), sulfonic acid derivatives, naphthoic acid, resorcinol
• Diazotization: Aromatic amine treated with sodium nitrite/hydrochloric acid forming diazonium salt
• Azo coupling: Diazonium compound coupled with 3-hydroxy-2-naphthoic acid to form azo bond
• Sulfonation: Sulfonated group introduced to partially increase water interaction
• Calcium salt formation: Product converted to calcium salt for stability and food-grade form
• Crystallization: Product crystallized and dried to obtain final pigment
• Chemical synthesis: Entirely synthetic; no natural sources

Where You’ll Find It

E180 is restricted to cheese surface coating only:

Primary Food Application (Only Approved Use):

• Cheese rind coating (ONLY APPROVED USE) – Red cheddar, mimolette, edam, gouda, and other cheese rinds; external color only
• Maximum use level: Surface coating; not specified quantitatively but strictly limited to visible coating

Non-food applications (widespread industrial use):

• Printing inks (PRIMARY USE) – standard magenta in three and four-color printing processes
• Paints and coatings – industrial paints, automotive finishes
• Textile dyeing – fabric and fiber coloring
• Cosmetics – lip balms, cosmetic products; component in some lipsticks
• Plastics and rubber – colorization of plastic products

Regulatory scope (severe restrictions): EU Authorization—E180 approved ONLY for surface coating of cheese; NO other food applications permitted. FDA (USA)—NOT approved for food use; banned.

Application scope: E180 is the most restricted synthetic food colorant—approved only for this single specific application (cheese coating), reflecting the limited nature of its utility in foods.

Why Did E180 Get This Unusual Restricted Approval?

E180’s approval for cheese coating only (and not for other foods) reflects its unique physical properties and the minimal exposure associated with this specific application.

E180 was approved because:

• Water insolubility: E180 cannot dissolve in water or food; remains only on surface
• Minimal absorption: Stays on cheese rind; not absorbed into cheese interior
• Minimal ingestion: Rind often removed before eating; even if eaten, pigment stays on surface
• Negligible dietary exposure: Total dietary exposure far lower than with soluble dyes in other foods
• Specific traditional use: Cheese coating is traditional/historical application; colorant predates modern regulatory system
• No viable alternatives: At time of approval, limited alternatives existed for this specific application
• Risk-benefit for this specific use: For surface cheese coating specifically, benefits justified approval despite azo dye class concerns

Notably: E180 is NOT approved for use in any other foods—not beverages, not baked goods, not confectionery. This restriction reflects regulatory judgment that the risks (azo dye class) outweigh benefits except for this specific minimal-exposure application.

Is It Safe?

E180 has regulatory approval from the EU for cheese coating, but with significant safety caveats and it is banned in numerous countries.

Regulatory approval status:

• EU: Approved for cheese coating only (2010 EFSA re-evaluation) with specified restrictions
• FDA (USA): NOT approved for food use; banned for safety concerns
• Health Canada: NOT approved
• Multiple countries: Banned in several jurisdictions despite EU approval
• JECFA: Evaluated; ADI of 1.5 mg/kg established but with reservations
• EFSA 2010 re-evaluation: Approved for cheese coating; noted areas of uncertainty

Health concerns documented:

• Allergic reactions: As azo dye, can cause hypersensitivity in sensitive individuals; documented cases of skin reactions
• Asthma exacerbation: May worsen asthma symptoms, particularly in aspirin-sensitive individuals
• Hyperactivity potential: Azo dyes associated with potential behavioral/hyperactivity effects in children (research ongoing/debated)
• Salicylate intolerance: Individuals intolerant to salicylates may react to E180
• Skin reactions: Contact dermatitis, urticaria, rash documented in sensitive individuals
• Rhinitis/inflammation: May worsen rhinitis and inflammatory conditions
• Azo dye metabolism: Like other azo dyes, gut bacteria can cleave -N=N- bond producing potentially harmful metabolites
• Limited toxicological data: Fewer comprehensive studies available compared to other food colorants

Comparison: E180 vs Other Food Colorants

The Bottom Line

E180 (Lithol Rubine BK) is a synthetic red azo dye pigment approved exclusively for coating cheese rinds, where it remains on the surface and is minimally ingested. It is one of the most restricted approved food colorants—allowed for only this single specific application due to the minimal dietary exposure involved.

Key features: E180 is water-insoluble; remains on cheese surface; minimal ingestion; minimal dietary exposure; restricted to cheese coating only; BANNED in USA and multiple jurisdictions.

For consumers: If you have asthma, aspirin sensitivity, or documented sensitivity to food dyes—remove cheese rind before eating or avoid E180-coated cheeses entirely. For general population, the minimal dietary exposure from cheese coating suggests low risk, though the widespread industrial use of E180 in inks and cosmetics (not food) suggests regulatory caution about this compound.

Bottom recommendation: E180 is safe for its specific restricted application (cheese coating) due to minimal dietary exposure. However, because it is an azo dye with documented allergic and hyperactivity concerns (even if minimal at this exposure level), and because it is banned in the USA and other jurisdictions, consumers may reasonably choose to avoid it—particularly by removing cheese rind before eating, which eliminates the source of E180 exposure entirely.