Prussian blue can produce hydrogen cyanide when exposed to strong acids.
From the en.wikipedia.org
The form of prussian blue required for the treatment of humans or animals is a special grade.
From the en.wikipedia.org
Cs is to feed to animals a little prussian blue.
From the en.wikipedia.org
The cyanide is so tightly bonded to the iron that it is safe for a human to eat several grams of prussian blue per day.
From the en.wikipedia.org
Prussian blue can release cyanide.
From the sciencedaily.com
It's smaller than most, and has a light prussian blue ceiling with paintings using all natural colours from the surrounding area other than the blue.
From the au.news.yahoo.com
An added advantage of the prussian blue is that the caesium which is stripped from the animal in the droppings is in a form which is not available to plants.