You can actually consume a _lot_ of cyanide without negative consequences, your body can detoxify it easily in small quantities. You can dissolve a lethal dose of cyanide in a bottle of water, and you'll be fine if you drink it in small sips over the course of a day.

Cyanide is so toxic because it has a high affinity for iron ions, so it deactivates iron-containing enzymes that are crucial for respiration. But in ferrocyanide it is _already_ combined with iron.

Ferrocyanide compounds like Prussian blue are even sometimes used as an antidotes for heavy metal poisoning.

Huh, why do they use that in the EU over silicates? (That was why I referenced sand btw).

Also, not sure what the relevance to iodine is?

Incidentally, iodine isn't easily sourced in some countries, due to soils that contain very little of it. My country (NZ) used to have a very real goitre problem until the introduction of iodised salt in the 1920s.

I'm sure you're aware that ferrocyanide is not the same thing as cyanide - the cyanide is bound so tightly to the iron center that it is nontoxic.

That is not potassium cyanide.