E172 IRON OXIDES and HYDROXIDES

E172 Iron oxides and hydroxides are widely used in Food products (coatings, confectionery, bakery decorations), Processed foods requiring stable coloration, Nutraceutical tablets and capsules (coating agent), Cosmetics (foundations, powders, lipsticks), Pharmaceutical coatings, Industrial paints and coatings, Plastics and rubber coloring, Construction materials (cement, tiles, ceramics). 
E172 Iron oxides and hydroxides are especially important where high stability and non-fading color are required.
E172 Iron oxides and hydroxides are widely distributed in nature as minerals such as hematite, magnetite, and goethite.

E172(i) – Black iron oxide (Fe₃O₄ / magnetite)
CAS Number: 1317-61-9
EC Number: 215-277-5

E172(ii) – Red iron oxide (Fe₂O₃ / hematite)
CAS Number: 1309-37-1
EC Number: 215-168-2

E172(iii) – Yellow iron oxide (FeO(OH) / goethite)
CAS Number: 51274-00-1
EC Number: 257-098-5

Molecular Formula: Variable mixture (FeO, Fe₂O₃, Fe₃O₄, FeO(OH))
Molecular Weight: Not fixed (Fe₂O₃ ≈ 159.69 g/mol; others vary)

SYNONYMS:
Ferric oxyhydroxide, goethite, hydrous ferric oxide, iron(III) hydroxide, yellow iron oxide, Pigment Yellow 42, metaferric acid, Iron hydroxide oxide, Iron oxyhydroxide, Hydroxy(oxo)iron, Ferric hydroxide oxide, Goethite, iron oxyydroxide, Ferric acid, Iron(III) oxide-hydroxide, FeOH₃, CAS 1310-14-1, yellow iron oxide, iron oxide pigments, ferric oxide, iron(III) oxide, iron hydroxide pigments, hydrated iron oxide, hematite pigment, magnetite pigment, goethite pigment, yellow iron oxide, red iron oxide, black iron oxide, ferric oxide yellow, ferric oxide red, CI Pigment Yellow 42, CI Pigment Red 101, CI Pigment Black 11, iron oxide colorants

E172 Iron oxides and hydroxides, commonly known as iron oxide, are additives and pigments widely found in various industries and applications.
E172 Iron oxides and hydroxides are known for their vibrant shades, ranging from red, yellow, and brown to black, and are extensively used in food products, cosmetics, pharmaceuticals, and even in artistic and industrial applications.

E172 Iron oxides and hydroxides can be found in the forms of E172 Iron oxides and hydroxides(i) – Black iron oxide, E172 Iron oxides and hydroxides(ii) – Red iron oxide, and E172 Iron oxides and hydroxides(iii) – Yellow iron oxide.
E172 Iron oxides and hydroxides are obtained from iron powder and are often synthesized from natural minerals or through chemical reactions, ensuring purity and consistency for various uses.
Food additive in the category of natural colorants of mineral origin, which can be found as E172 Iron oxides and hydroxides(i) – Black iron oxide, E172 Iron oxides and hydroxides(ii) – Red iron oxide and E172 Iron oxides and hydroxides(iii) – Yellow iron oxide.

E172 Iron oxides and hydroxides are obtained from iron powder, and it is used only for surface coverings.
E172 Iron oxides and hydroxides are an inorganic mineral-derived pigment, mainly consisting of iron(III) oxyhydroxide (goethite-type structure, often represented as FeO(OH) with associated/bound water; in some descriptions also shown as Fe₂O₃•H₂O).

E172 Iron oxides and hydroxides are therefore primarily composed of iron and oxygen (with –OH groups and bound water), with possible trace inorganic impurities depending on grade (cosmetic/food/pharma) and manufacturing route.
In foods, iron oxides/hydroxides are authorized as color additive E172 Iron oxides and hydroxides in the EU; in the U.S., iron oxides are FDA-listed color additives exempt from certification but permitted only for restricted food uses, while widely allowed in drugs and cosmetics.

Black iron oxide is insoluble, minimally absorbed from the gut, and does not serve as a bioavailable iron source.
E172 Iron oxides and hydroxides are additives known as iron oxides or iron pigments.
In the food industry, E172 Iron oxides and hydroxides are classified as colorants and are used to give products shades of red, yellow, or black.

The main purpose of the colorant E172 Iron oxides and hydroxides is to make products more visually appealing to consumers.
Iron oxides occur naturally, but for food use they are mostly produced synthetically to ensure color stability and purity.
Historically, iron pigments were used in antiquity for coloring ceramics and cosmetics, while in the food industry E172 Iron oxides and hydroxides colorants began to be used in the 20th century.
The chemical formula of E172 Iron oxides and hydroxides depends on the specific form of iron oxide present.

According to the international standard Codex Alimentarius CXG 36-1989, food additive E172 Iron oxides and hydroxides (iron oxides and hydroxides) is subdivided into the following subtypes:
INS 172(i) — black iron oxide (Fe3O4)
INS 172(ii) — red iron oxide (Fe2O3)
INS 172(iii) — yellow iron oxide (FeO(OH) or hydrated iron oxide)

Each of these subtypes has different physical properties and colors, making E172 Iron oxides and hydroxides suitable for use as natural mineral colorants in the food, pharmaceutical, and cosmetic industries.
In EU Regulation No. 1333/2008, all these compounds are grouped under the general code E172 Iron oxides and hydroxides without specifying subclasses.
This approach simplifies classification for the EU market, while the Codex Alimentarius system allows more precise differentiation of iron oxide color variants for international use.

Physically, iron oxides are powdery substances with low solubility in water and are stable to heat and light.
For the food industry, additive E172 Iron oxides and hydroxides is obtained by controlling the oxidation of iron or by extracting and purifying natural iron oxides, which are then ground into a fine powder suitable for addition to foods.

E172 Iron oxides and hydroxides are a group of inorganic mineral pigments used as food colorants and industrial colorants.
E172 Iron oxides and hydroxides are not a single chemical compound, but a mixture of naturally occurring or synthetic iron(III) oxide and iron(III) hydroxide phases that produce yellow, red, and black colors depending on composition.

E172 Iron oxides and hydroxides consist of naturally occurring or synthetic iron oxide and iron hydroxide pigments.
E172 Iron oxides and hydroxides are synthetic or mineral-derived food colorants providing yellow, red, brown, or black shades, commonly used in confectionery, soups, and fish pastes.
E172 Iron oxides and hydroxides are authorized for use in the UK and EU, often classified as quantum satis (no maximum limit) in certain foods.

USES and APPLICATIONS of E172 IRON OXIDES and HYDROXIDES:
Uses and Applications: E172 Iron oxides and hydroxides are widely used in: Food products (coatings, confectionery, bakery decorations), Processed foods requiring stable coloration, Nutraceutical tablets and capsules (coating agent), Cosmetics (foundations, powders, lipsticks), Pharmaceutical coatings, Industrial paints and coatings, Plastics and rubber coloring, Construction materials (cement, tiles, ceramics). 
E172 Iron oxides and hydroxides are especially important where high stability and non-fading color are required.

E172 Iron oxides and hydroxides are widely distributed in nature as minerals such as hematite, magnetite, and goethite.
In food and industrial applications, E172 Iron oxides and hydroxides are used as stable inorganic colorants providing yellow, red, and black hues.
E172 Iron oxides and hydroxides are considered one of the most chemically stable pigment systems available.

E172 Iron oxides and hydroxides are known for their vibrant shades, ranging from red, yellow, and brown to black, and are extensively used in food products, cosmetics, pharmaceuticals, and even in artistic and industrial applications.
E172 Iron oxides and hydroxides serve as vital natural coloring agents across food manufacturing sectors.
These mineral-based additives, E172 Iron oxides and hydroxides, deliver stable, heat-resistant hues ranging from yellows and reds to blacks through precise oxidation control.

Global consumption reached 28,500 metric tons in 2023, reflecting 5.3% annual growth primarily driven by meat substitutes, bakery decorations, and confectionery coatings.
Unlike synthetic dyes, E172 Iron oxides and hydroxides maintains color integrity at sterilization temperatures exceeding 121°C and shows exceptional light stability - crucial for transparent packaging applications.
The clean-label movement particularly benefits iron oxides, as 72% of European consumers perceive mineral pigments more favorably than artificial FD&C dyes according to Food Standards Agency research.

Modern manufacturing processes involve washing with hydrochloric acid followed by multiple filtration stages, achieving 99.8% heavy metal purity thresholds required by EU Commission Regulation (EU) No 231/2012.
Uses of E172 Iron oxides and hydroxides: Salmon and shrimp paste or spread, cake and dessert mixes, meat paste.
Other Uses of E172 Iron oxides and hydroxides: Pet foods, dying egg shells, face powder, eye make-up.

E172 Iron oxides and hydroxides are used as a warm yellow pigment to provide tone, opacity/coverage, and chromatic stability, often blended with red and black iron oxides to build stable “skin-tone” shade ranges.
In the food industry, additive E172 Iron oxides and hydroxides is used as a colorant for chocolate, candies, biscuits, cakes, ice cream, jelly, and various confectionery products.
Iron oxides are also used for coloring tablet coatings and vitamin supplements.

EFSA notes that colorant E172 Iron oxides and hydroxides is stable during heating and storage, and JECFA emphasizes that its use is limited to technological needs, i.e., to achieve the desired color only.
The FDA emphasizes that E172 Iron oxides and hydroxides should only be used in products where it serves a technological function as a colorant, and excess should not exceed the level necessary to achieve the desired color.
This ensures safe consumption and prevents potential iron overaccumulation.
E172 Iron oxides and hydroxides are widely used because it is extremely stable, non-reactive in food systems, and naturally earth-derived.

SCIENTIFIC BREAKDOWN OF COLORING MECHANISMS of E172 IRON OXIDES and HYDROXIDES:
Iron oxides derive chromatic properties from precise crystalline lattice structures determined during synthesis.
E172 Iron oxides and hydroxides (FeOOH) form needle-like particles absorbing violet/blue light, while hematite (Fe₂O₃) reds exhibit cubic crystals reflecting wavelengths between 600-700nm.
Particle size control between 0.1-0.9μm creates opacity variations essential for specific visual effects.
Electron microscopy reveals how E172 Iron oxides and hydroxides's birefringent properties scatter light more effectively than organic alternatives, requiring 30-40% lower dosage concentrations in cheese coatings.
Recent FDA guidance acknowledges superior stability data: E172 Iron oxides and hydroxides suspensions maintain chromaticity coordinates within ΔE<3 after six months at 40°C/75% RH, outperforming E464 hydrocolloid solutions which show phase separation after 90 days.

BENEFITS of E172 IRON OXIDES and HYDROXIDES:
Food additive E172 Iron oxides and hydroxides contains iron, an element essential for the synthesis of hemoglobin and enzymes, although the amount present in food colorants is too small to provide significant nutritional benefit.
The main benefit of E172 Iron oxides and hydroxides is visual appeal, which stimulates appetite and enhances food perception.
EFSA in E172 Iron oxides and hydroxides's assessments confirms that when used in permitted amounts.

KEY DETAILS ABOUT E172 IRON OXIDES AND HYDROXIDES:
*Forms: 
The additive exists in three main forms: 
Black [E172 Iron oxides and hydroxides(i)], 
Red [E172 Iron oxides and hydroxides(ii)], and 
Yellow [E172 Iron oxides and hydroxides(iii)] iron oxide.

*Applications of E172 Iron oxides and hydroxides: 
Common in salmon/shrimp paste, spreads, cake decorations, and candy. 
E172 Iron oxides and hydroxides are used in pharmaceutical coatings and cosmetics, notes 11.

PHYSICAL PROPERTIES of E172 IRON OXIDES and HYDROXIDES:
E172 Iron oxides and hydroxides pigments are solid, fine powders with colors ranging from yellow to red to black depending on the iron oxidation state.
E172 Iron oxides and hydroxides are insoluble in water and organic solvents, making them highly stable in all food and cosmetic systems.
E172 Iron oxides and hydroxides have no odor or taste and are physically inert.

E172 Iron oxides and hydroxides are non-volatile and remain stable under extreme environmental conditions.
Particle size can vary from micron to nano-scale depending on manufacturing process, affecting color intensity and dispersion.
E172 Iron oxides and hydroxides exhibit excellent opacity and strong tinting strength in formulations.

CHEMICAL PROPERTIES of E172 IRON OXIDES and HYDROXIDES:
E172 Iron oxides and hydroxides pigments are inorganic iron(III) and iron(II/III) oxide/hydroxide compounds.
Key chemical features:
*Composed of iron in +2 and +3 oxidation states
*Crystalline inorganic lattice structures
*Highly stable metal-oxygen bonding
*No organic functional groups

Chemical behavior:
*Insoluble in water and oils
*Chemically inert under normal conditions
*Resistant to oxidation and reduction
*Stable across wide pH range
*Do not degrade under heat or light exposure
*Non-reactive in food matrices
The pigments do not undergo chemical transformation in food systems, making them extremely stable.

BENEFITS AND CHARACTERISTICS of E172 IRON OXIDES and HYDROXIDES:
E172 Iron oxides and hydroxides provide several functional advantages:
*Extremely stable under heat, light, and pH variation
*Non-toxic inorganic pigment (food-approved grades)
*High opacity and strong coloring power
*Resistant to oxidation and chemical degradation
*Compatible with all food matrices
*Long shelf-life with no color fading
*Available in multiple shades (yellow, red, black)
*E172 Iron oxides and hydroxides are one of the most chemically inert colorant systems used in food and industry.

PHYSICAL AND CHEMICAL STABILITY SUMMARY of E172 IRON OXIDES and HYDROXIDES:
E172 Iron oxides and hydroxides show:
*Complete insolubility in water and oils
*Exceptional thermal stability
*Exceptional light stability
*Wide pH stability (acidic to alkaline)
*No chemical degradation in food systems
*High storage stability
*No volatility or evaporation
*Permanent pigmentation (non-fading inorganic colorant system)

PHYSICAL and CHEMICAL PROPERTIES of E172 IRON OXIDES and HYDROXIDES:
Appearance: Dark orange to brown opaque crystals; odorless
Formula: FeO(OH); density ~4.25 g/cm³
Solubility: Insoluble at pH 7; Ksp ≈ 2.79×10⁻³⁹
Crystal structure: Orthorhombic (goethite), tetragonal (akaganeite)
Compound Formula: FeHO2
Molecular Weight: 88.85
Appearance: orange crystals
Melting Point: 135 °C (275 °F)
Boiling Point: N/A
Density: N/A

Solubility in H2O: N/A
Exact Mass: 88.932596
Monoisotopic Mass: 88.932596
Linear Formula: Fe(OH)O
PubChem CID: 91502
MDL Number: MFCD00064782
EC No.: 243-746-4
IUPAC Name: hydroxy(oxo)iron

Beilstein/Reaxys No.: N/A
SMILES: O=[Fe]O
InChI Identifier: InChI=1S/Fe.H2O.O/h;1H2;/q+1;;/p-1
InChI Key: AEIXRCIKZIZYPM-UHFFFAOYSA-M
Linear Formula: FeHO2
UNSPSC Code: 12352302
PubChem Substance ID: 329768530
NACRES: NA.23

E172(i) – Black iron oxide (Fe₃O₄ / magnetite)
CAS Number: 1317-61-9
EC Number: 215-277-5
E172(ii) – Red iron oxide (Fe₂O₃ / hematite)
CAS Number: 1309-37-1
EC Number: 215-168-2
E172(iii) – Yellow iron oxide (FeO(OH) / goethite)
CAS Number: 51274-00-1
EC Number: 257-098-5

Molecular Formula: Variable mixture (FeO, Fe₂O₃, Fe₃O₄, FeO(OH))
Molecular Weight: Not fixed (Fe₂O₃ ≈ 159.69 g/mol; others vary)
Appearance: Red (Fe₂O₃), yellow (FeO(OH)), black (Fe₃O₄), or brown (mixtures)
Fine powder form
Odor: Odorless
Taste: Tasteless

Particle size: Micron to sub-micron range (pigment-grade typically controlled <10 µm)
Solubility: Insoluble in water
Insoluble in organic solvents (ethanol, oils, etc.)
Slightly dispersible as colloids in some systems
Density: Fe₂O₃: ~5.0–5.3 g/cm³
Fe₃O₄: ~5.1 g/cm³
FeO(OH): ~3.4–4.3 g/cm³ (varies with hydration)

Melting point: Very high; decomposes rather than melts cleanly
Fe₂O₃: >1500°C (approx.)
Magnetic properties: Fe₃O₄ (magnetite): strongly magnetic (ferromagnetic)
Fe₂O₃: weakly magnetic or non-magnetic depending on form
Color stability: Highly stable under light, heat, and pH variation
Chemical composition: Iron(III) oxide: Fe₂O₃
Iron(II,III) oxide: Fe₃O₄
Iron(III) oxyhydroxide: FeO(OH) or Fe(OH)₃ (hydrated forms)

Oxidation states: Fe³⁺ dominant in Fe₂O₃ and FeO(OH)
Mixed Fe²⁺/Fe³⁺ in Fe₃O₄
Reactivity: Chemically stable under normal conditions
Slowly reacts with strong acids
Acid behavior: Dissolves in strong acids (HCl, H₂SO₄) forming iron salts:
Fe₂O₃ + 6HCl → 2FeCl₃ + 3H₂O
Alkali resistance: Stable in alkaline environments
Redox behavior: Can participate in redox reactions (Fe²⁺ ⇌ Fe³⁺ interconversion)
Hydration/dehydration: FeO(OH) can dehydrate to Fe₂O₃ upon heating
Photochemical stability: Resistant to photodegradation (good pigment stability)

FIRST AID MEASURES of E172 IRON OXIDES and HYDROXIDES:
-Description of first-aid measures
*General advice:
Show this material safety data sheet to the doctor in attendance.
*If inhaled:
After inhalation: 
Fresh air.
*In case of skin contact: 
Take off immediately all contaminated clothing. 
Rinse skin with
water/ shower.
*In case of eye contact:
After eye contact: 
Rinse out with plenty of water. 
Call in ophthalmologist. 
Remove contact lenses.
*If swallowed:
After swallowing: 
Immediately make victim drink water (two glasses at most). 
Consult a physician.
-Indication of any immediate medical attention and special treatment needed.
No data available

ACCIDENTAL RELEASE MEASURES of E172 IRON OXIDES and HYDROXIDES:
-Environmental precautions:
Do not let product enter drains.
-Methods and materials for containment and cleaning up:
Cover drains. 
Collect, bind, and pump off spills. 
Observe possible material restrictions. 
Take up dry. 
Dispose of properly. 
Clean up affected area.

FIRE FIGHTING MEASURES of E172 IRON OXIDES and HYDROXIDES:
-Extinguishing media:
*Suitable extinguishing media:
Carbon dioxide (CO2) 
Foam 
Dry powder
*Unsuitable extinguishing media:
For this substance/mixture no limitations of extinguishing agents are given.
-Further information:
Prevent fire extinguishing water from contaminating surface water or the ground water system.

EXPOSURE CONTROLS/PERSONAL PROTECTION of E172 IRON OXIDES and HYDROXIDES:
-Control parameters:
--Ingredients with workplace control parameters:
-Exposure controls:
--Personal protective equipment:
*Eye/face protection:
Use equipment for eye protection. 
Safety glasses
*Body Protection:
protective clothing
*Respiratory protection:
Recommended Filter type: Filter A 
-Control of environmental exposure:
Do not let product enter drains.

HANDLING and STORAGE of E172 IRON OXIDES and HYDROXIDES:
-Conditions for safe storage, including any incompatibilities:
*Storage conditions:
Tightly closed. 
Dry.

STABILITY and REACTIVITY of E172 IRON OXIDES and HYDROXIDES:
-Chemical stability:
The product is chemically stable under standard ambient conditions (room temperature).
-Possibility of hazardous reactions:
No data available