 Kidneys are the organ for ferrocyanide toxicity.Sodium ferrocyanide is produced industrially from hydrogen cyanide, ferrous chloride, and calcium hydroxide, the combination of which affords Ca2[Fe(CN)6].A solution of this salt is then treated with sodium salts to precipitate the mixed calcium-sodium salt CaNa2[Fe(CN)6], which in turn is treated with sodium carbonate to give the tetrasodium salt.