Synthetic iron oxide

CAS 1309-37-1

Listed as a colour and a processing aid by the US.

Listed as colours (US) · processing aids (US)
Chemical structure of Synthetic iron oxide, from PubChem compound 56841934
Structure from PubChem CID 56841934 (National Library of Medicine, public domain). A depiction of one compound: where a listing covers a family, or a substance has no single structure, this page shows none.

Synthetic iron oxides give red, yellow, brown and black, used in confectionery, sausage casings and pet food. They are the same pigments as ochre and rust, made to a controlled purity.

Where it is and isn’t permitted

Status of Synthetic iron oxide by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
Australia and New ZealandFood Standards Australia New ZealandPermitted, with conditions

47 food categories

no numerical limit (good manufacturing practice)

Show every food category
  • 0.2 Colourings — GMP
  • 0.3 Flavourings — GMP
  • 1.1.2 Liquid milk products and flavoured liquid milk — GMP
  • 1.2.2 Fermented milk products and rennetted milk products — GMP
  • 1.3 Condensed milk and evaporated milk — GMP
  • 1.4.2 Cream products (flavoured, whipped, thickened, sour cream etc) — GMP
  • 1.5 Dried milk, milk powder, cream powder — GMP
  • 1.6 Cheese and cheese products — GMP
  • 11.1.1 Rainbow sugar — GMP
  • 11.4 Tabletop sweeteners — GMP
  • 12.1.2 Reduced sodium salt mixture — GMP
  • 12.1.3 Salt substitute — GMP
  • 12.3 Vinegars and related products — GMP
  • 12.5 Yeast and yeast products — GMP
  • 12.6 Vegetable protein products — GMP
  • 13.3 Formulated meal replacements and formulated supplementary foods — GMP
  • 13.4 Formulated supplementary sports foods — GMP
  • 13.5 Food for special medical purposes — GMP
  • 14.1.1.2 Carbonated, mineralised and soda waters — GMP
  • 14.1.2.1 Fruit and vegetable juices — GMPFor juice separated by other than mechanical means only.
  • 14.1.2.2 Fruit and vegetable juice products — GMP
  • 14.1.3 Water based flavoured drinks — GMP
  • 14.1.4 Formulated Beverages — GMP
  • 14.2.3 Wine based drinks and reduced alcohol wines — GMP
  • 14.2.4.1 Fruit wine products and vegetable wine products — GMP
  • 14.2.5 Spirits and liqueurs — GMP
  • 14.3 Alcoholic beverages not included in item 14.2 — GMP
  • 2.1 Edible oils essentially free of water — GMPNot for olive oil.
  • 2.2.1.2 Butter products — GMP
  • 2.2.1.3 Margarine and similar products — GMP
  • 2.2.2 Oil emulsions (<80% oil) — GMP
  • 20 Foods not included in items 0 to 14 — GMP
  • 3 Ice cream and edible ices — GMP
  • 4.3 Processed fruits and vegetables — GMP
  • 5.1 Chocolate and cocoa products — GMPPermitted on the surface of chocolate only.
  • 5.2 Sugar confectionery — GMP
  • 5.4 Icings and frostings — GMP
  • 6.3 Processed cereal and meal products — GMP
  • 6.4 Flour products (including noodles and pasta) — GMP
  • 7 Breads and bakery products — GMP
  • 8.2 Processed meat, poultry and game products in whole cuts or pieces — GMP
  • 8.3 Processed comminuted meat, poultry and game products, other than products listed in item 8.3.2 — GMPNot for sausage or sausage meat containing raw, unprocessed meat.
  • 8.4 Edible casings — GMP
  • 8.5 Animal protein products — GMP
  • 9.2 Processed fish and fish products — GMP
  • 9.3 Semi preserved fish and fish products — GMP
  • 9.4 Fully preserved fish including canned fish products — GMP
Food Standards Code, Schedule 15, S15—5and 46 further provisionsretrieved 2026-10-17
CanadaHealth CanadaNo listing matchedHealth Canada’s lists name additives without E or INS numbers, so this site matches them by exact name. A substance listed there under a name this site does not recognise has no row here.
European UnionEuropean Commission / EFSANo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
Great BritainFood Standards Agency / Food Standards ScotlandNo listed food uses foundThis site has not matched this substance to any food use on this jurisdiction’s list of authorised food additives. A food additive may be used only in foods that list names. Flavourings, enzymes, processing aids and added nutrients are regulated separately and do not appear on it.
JapanConsumer Affairs AgencyNo listing matchedThis site imports only Japan’s list of designated additives (Appended Table 1 to the Regulations for Enforcement of the Food Sanitation Act), matched by English name. Existing additives, natural flavouring agents and ordinary foods used as additives are permitted outside that list and are not imported, so an empty row does not show that Japan does not permit the substance.
South KoreaMinistry of Food and Drug SafetyNo listing matchedThis site imports Part III of South Korea’s Standards and Specifications for Food Additives, matched by CAS number, then INS number, then exact name. Mixed preparations and sanitisers are not imported, and an entry whose identifiers disagreed with a page’s is held for review, so an empty row does not show that South Korea does not permit the substance.
United StatesFood and Drug AdministrationPermitted21 CFR 73.200retrieved 2026-10-17
Codex AlimentariusCodex Alimentarius Commission / JECFANot listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited.

How much is permitted

A listing usually limits the quantity as well as the food. Only one of the forms that takes is a figure: quantum satis and good manufacturing practice permit the amount the technological effect requires and no more, which is a limit rather than the absence of one. Figures below are the range across every food category this page is listed in, and categories differ between regulators — see how much is permitted.

Australia and New Zealand—47 GMP
United States—1 no quantity stated

No regulator sets a figure for Synthetic iron oxide. That is not an absence of control: where the listing says quantum satis or good manufacturing practice, the quantity is limited to what the effect requires.

What it is made from

Produced synthetically rather than mined, because natural ores carry heavy metal impurities that the food grade must not.

  • Vegan
  • Vegetarian

Compare other additives on the dietary indexes.

CAS registry number
1309-37-1
InChIKey
YOBAEOGBNPPUQV-UHFFFAOYSA-N
PubChem
CID 56841934

Every name it appears under

71 recorded names. A label may use any of them.

CAS registry number

  • 1309-37-1

As it appears in regulation

  • Synthetic iron oxide

Other names

  • 11554 Red
  • Anchred standard
  • Anhydrous Ferric Oxide
  • Anhydrous Iron (III)
  • Anhydrous Iron (III) Oxide
  • Anhydrous iron oxide
  • Anhydrous oxide of iron
  • Armenian bole
  • Bayer S 11
  • Bayferrox 105M
  • Black oxide of iron
  • Calcotone Red
  • Caput mortuum
  • CCRIS 7330
  • Colcothar
  • Colloidal ferric oxide
  • COSMETIC RED OXIDE
  • Crocus martis adstringens
  • Deanox
  • E 172 RED
  • Eisenoxyd
  • English Red
  • Ferric oxide (anhydrous)
  • Ferric oxide (colloidal)
  • Ferric oxide [NF]
  • Ferric oxide, red [NF]
  • Ferric sesquioxide
  • Ferrous-ferric oxide
  • Ferrugo
  • Ferrum Oxydatum
  • Hematite 8124
  • Hematite mineral
  • HSDB 452
  • Indian Red
  • Iron oxide (Fe2O3)
  • Iron oxide dust
  • Iron oxide dust and Fume (Fe2O3)
  • Iron oxide,
  • Iron oxide, red
  • Iron Red
  • Iron sesquioxide
  • Iron trioxide
  • iron(3+) oxide
  • Iron(III) oxide
  • JEIPFZHSYJVQDO-UHFFFAOYSA-N
  • Jeweler's rouge
  • Jewelers rouge
  • Levanox Red 130A
  • Light Red
  • Mapico Red
  • Mars Brown
  • Mars Red
  • Natural hematite
  • Natural Red Oxide
  • Ochre
  • Prussian Brown
  • Quick rouge
  • Raddle
  • Red Ferric Oxide
  • Red Iron Oxide
  • RED IRON OXIDE R 1599D
  • Red oxide
  • Red oxide D3452
  • Red oxide D6984
  • Red oxide of iron
  • Rouge
  • Synthetic iron oxide
  • YOBAEOGBNPPUQV-UHFFFAOYSA-N

Systematic names

  • oxo(oxoferriooxy)iron

Hazard reference values

No reference value for this substance in the sources we hold.

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated rather than machine-read, and none has been written for this substance yet.

Common questions

Assembled from what is above, in the words the questions are usually asked in. Each answer is the same statement the relevant section makes, with the same citations behind it.

What is Synthetic iron oxide?
Synthetic iron oxides give red, yellow, brown and black, used in confectionery, sausage casings and pet food. They are the same pigments as ochre and rust, made to a controlled purity.
What is Synthetic iron oxide used for in food?
It is listed as a colour and a processing aid — the role the US assigns it. This page shows every function each regulator records, with the citation for each.
Is Synthetic iron oxide banned in Europe?
No. Synthetic iron oxide does not appear on the EU's list of authorised food additives, which is not the same as being banned: the EU permits an additive only where it has authorised it, and usually the reason for an absence is that no one applied. The EU has made no finding against this substance. It does mean it may not be used as a food additive in the EU today.
Where is Synthetic iron oxide permitted?
Of the seven regulators this site reads, Australia and New Zealand and the US permit it. Each permission is for named foods at named levels, not a blanket one; the table on this page gives them with citations.
Is Synthetic iron oxide vegan?
Yes. Synthetic iron oxide is not derived from animals, and is suitable for vegetarians. This page says what it is made from and how.

Sources for this page

  • anz retrieved 2026-10-17
  • ecfr retrieved 2026-10-17

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable: a JSON record of this additive is given on request —how to ask for access.

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