Sodium Ferrocyanide
The short version
An anti-caking agent in table salt — the cyanide is locked in an iron complex, but the name causes regular confusion.
It's permitted and generally considered safe, but there are a few reasons to be mindful — like sensitivities in some people, debated studies, or intake limits. The Safety section below explains the specifics.
Safety profile
EFSA (2018) set a group ADI of 0.03 mg/kg body weight per day for sodium, potassium and calcium ferrocyanide, expressed as ferrocyanide ion, and found no safety concern at current authorised uses. JECFA's earlier ADI (1974) is 0–0.025 mg/kg body weight, calculated as sodium ferrocyanide. The iron-cyanide complex is one of the most stable known and does not release free cyanide in the digestive tract. The toxicological concern is the complex itself, not cyanide release. Russia banned it in 2018 over uncertainty about long-term iron-cyanide accumulation.
Sources
- EFSA — Re-evaluation of sodium ferrocyanide (E 535), potassium ferrocyanide (E 536) and calcium ferrocyanide (E 538) as food additives (2018) — EFSA (EFSA Journal 2018;16(7):5374, PMC copy), 2018. Current EFSA group ADI; no safety concern at authorised uses; low absorption
- WHO JECFA database — Sodium ferrocyanide (INS 535) — WHO / JECFA, 1974. JECFA ADI 0–0.025 mg/kg bw
- 21 CFR 172.490 — Yellow prussiate of soda — US eCFR (Office of the Federal Register), 2026. US permits it as anticaking agent in salt up to 13 ppm
- EUR-Lex — Regulation (EC) No 1333/2008, consolidated text 18.08.2026 (Annex II, salt and salt substitutes) — EUR-Lex (European Union), 2026. EU permits ferrocyanides in salt and salt substitutes at 20 mg/kg
Checked against these sources on .
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