How about that silicate?
Asbestos is a group of naturally occurring, toxic, carcinogenic and fibrous
silicate minerals.

Also there is those damn calcium bearing kidney stones.
I bet there is a non zero chance of getting some asbestos in your salt from cheap calcium silicate production methods
Its also rather insoluble. I wonder if it can be a nucleation point for kidney stones, since small particles might permeate tissues, and accumulate in preferred areas, compared to very soluble ferricyanide which will be flushed from your body quickly due to its high solubility. Something along the lines of a seed crystal.
It really seems that all these feel good replacements we got for traditional chemicals is just more complicated and worse lol