E538 / Acidity regulators & anti-caking agents
Calcium ferrocyanide
Safety in brief
Safe
Recorded EatMatrix rating, not a new clinical review. The amount, your sensitivities and country rules still matter.
- Watch for
- No allergen or sensitivity is recorded for this ingredient here. Check the whole product label; this is not an allergen-free guarantee.
- Our advice
- Read the whole food label and consider how often you eat the product. A name or E number does not tell you the amount, and an ingredient rating cannot assess the entire food.
What it is
Calcium ferrocyanide is an anticaking agent occasionally used in salt to prevent clumping, working the same way as the sodium and potassium ferrocyanides. The cyanide is tightly bound to iron and is not released under normal food-handling conditions. EFSA and the FDA consider it safe within permitted use levels.
Also appears on labels as: Calcium ferrocyanide, Calcium hexacyanoferrate, Calcium hexacyanoferrate(II), Ca2[Fe(CN)6], E538, E 538, E-538, INS 538, Food additive 538, Anti-caking agent E538, Ferrocyanure de calcium, Ferrocyanuro de calcio.
Dietary information
- Vegan
- Yes
- Halal
- Yes
- Gluten-free
- Yes
- Allergens
- None recorded
Recorded ingredient information. Check the product label or certification: sources, other ingredients and cross-contact can vary.
Research & body effects
Health notes from our ingredient record
- Considered safe at permitted use levels; no toxicity concern established from normal dietary use.
- Theoretical cyanide release requires extreme conditions not typical of food handling or digestion.
Other references from our ingredient record
These links come from the original ingredient record. They are separate from the source reviews above and have not all been checked for the exact ingredient, amount consumed or claim. Dates are shown newest first.
- Re‐evaluation of sodium ferrocyanide (E 535), potassium ferrocyanide (E 536) and calcium ferrocyanide (E 538) as food additives — EFSA Panel on Food Additives, EFSA Journal (2018). Official EFSA scientific opinion (bibliographic reference, imported 2026-10-13). It covers the additive as a group assessment and is not an individual human study; read the opinion for its findings.
Country rules
Country checks for E538
Permission depends on the market, type of food, amount and conditions. A scientific opinion or an E-number alone does not establish a legal use. These checks are separate from the stored EatMatrix rating.
Compare all eight markets and their sources
| Market | What is checked |
|---|---|
| European Union | Regulation (EC) 1333/2008, Annex II Part B, version , contains the exact code E538: Calcium ferrocyanide. Listing alone does not allow every food use. Part E food categories, limits, specifications and applicable later acts still need a product-specific check. Source read: . |
| Great Britain | The FSA register record for E538 (Calcium ferrocyanide) lists “Authorised” in England, Scotland and Wales. Register updated: 01 April 2025; record checked: . Food-specific conditions and specifications still need a separate legal check. |
| United States | Complete current-use review pending. Any scoped provision in the label guide above applies only to the stated use. FDA explains the applicable food-additive and GRAS framework. |
| Northern Ireland | Review pending. Check the applicable EU rules and territory arrangements; the GB register alone does not establish this status. FSA guidance is a starting source, not a verified permission for this entry. |
| Canada | No exact named entry located in the reviewed additive lists No exact named food-additive entry was located in the 15 current lists for Calcium Ferrocyanide. Potassium and sodium ferrocyanides are different salts. EatMatrix reading: Do not claim a permitted additive use from this review. Exact preparation, intended use and any applicable separate legal provision need confirmation; this table result is not a toxicology verdict or proof of a universal ban. Name and category review: . This describes the legal source check, not a finding that the ingredient is safe, unsafe or untested. Sources and names checkedNames checked: Calcium ferrocyanide; Calcium Ferrocyanide. All 15 Health Canada permitted-additive lists were checked by exact name, with the reviewed alternatives above. E-numbers alone are not Canadian ingredient names. The Justice Canada consolidation read was current to 21 September 2026. A complete product decision also requires its composition, specifications, intended food and use, quantities, applicable separate provisions and any later changes. |
| Australia | Review pending. Food Standards Code permissions and conditions need an additive-specific check. FSANZ food-additive rules is a starting source, not a verified permission for this entry. |
| New Zealand | Review pending. Food Standards Code permissions and conditions need an additive-specific check. FSANZ food-additive rules is a starting source, not a verified permission for this entry. |
| Japan | Review pending. The relevant list, identity and use standards need an additive-specific check. CAA food-additive lists is a starting source, not a verified permission for this entry. |
Sources & review status
Check what each source covers: an authority’s conclusion, a research finding and a country’s legal permission answer different questions.
What this guide covers
- Official assessment sources
- Commission-listed EFSA references for E538. Bibliographic identity checked; latest findings and current use rules need separate review.
- Original ingredient record
- 1 research link; newest recorded date: . Sources added separately to this guide are not included in this count.
This guide brings together our ingredient record and the dated sources shown here. Missing information describes a gap in this guide; it does not mean an ingredient is untested, safe or harmful. This is not a complete review of every study, preparation or current country rule. The amount in a product and how it is used still matter.
How to read the ratings, research and country checksAgency labels recorded by EatMatrix
These are imported database classifications, not verified current statements from each authority. Use the dated official sources below for their actual scope and conclusions.
| Authority | Database label |
|---|---|
| FDA | Safe |
| WHO | Safe |
| EFSA | Safe |
| FSANZ | Safe |
| Japan | Safe |
| UK FSA | Safe |
| Health Canada | Safe |
Official assessment sources for E538
The European Commission’s re-evaluation table lists official EFSA documents for this additive. Their identifiers and subjects were checked against publisher bibliographic records. A missing research link in the EatMatrix database does not mean the additive has never been assessed.
Name in the Commission table: Calcium ferrocyanide.
- Re‐evaluation of sodium ferrocyanide (E 535), potassium ferrocyanide (E 536) and calcium ferrocyanide (E 538) as food additives
EFSA scientific opinion. Published: .
These are assessment references, including historical or group assessments. They do not establish the latest scientific conclusion, a human health benefit or risk, or current permission to use the additive in a particular food. Later assessments, corrections and food-use conditions need separate review. The recorded EatMatrix rating above is unchanged.
European Commission re-evaluation table, status as of . EatMatrix checked this bibliography on .
Database updated: . What does an E number mean on a food label?
Common questions
Frequently asked questions
What is EatMatrix's recorded rating for E538?
The recorded EatMatrix rating for E538 (Calcium ferrocyanide) is “Safe”. It is calculated from labels stored in our ingredient database. These labels are not verified current regulator decisions or country permissions. A database update date is not a scientific review date.
Is E538 vegan, halal or gluten-free?
According to our ingredient data for Calcium ferrocyanide — vegan: yes, vegetarian: yes, halal: yes, kosher: yes, gluten-free: yes, dairy-free: yes. Manufacturing sources can vary between products; check the label if it matters to you.
What is E538 and why is it used?
Calcium ferrocyanide is an anticaking agent occasionally used in salt to prevent clumping, working the same way as the sodium and potassium ferrocyanides. The cyanide is tightly bound to iron and is not released under normal food-handling conditions. EFSA and the FDA consider it safe within permitted use levels.
Does E538 contain allergens?
No known allergens are recorded for Calcium ferrocyanide.
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This page shows information and classifications recorded in our ingredient database. Current scientific and market-specific verification remains pending as described above. It is general information, not medical advice.