E538 · Calcium ferrocyanide
- WHO
- Safe
- FDA
- Safe
- EFSA
- Safe
- FSANZ
- Safe
- Japan
- Safe
- UK FSA
- Safe
- Health Canada
- Safe
What is E538?
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.
What the evidence says
- 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.
Frequently asked questions
Is E538 safe?
Our overall verdict for E538 (Calcium ferrocyanide) is “Safe”, based on the most cautious of the major regulators’ positions — FDA: safe; WHO: safe; EFSA: safe; FSANZ: safe; Japan: safe; UK FSA: safe; Health Canada: safe.
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 summarises publicly available regulatory assessments and research. It is general information, not medical advice. Sources: EFSA, FDA, WHO and the studies linked above.