I thought cyanide was pretty much eliminated except for industrial processes. It is no longer available in the retail market. I remember as a kid dad bought cyanide eggs at the feed store to kill gophers. Drop a pellet down their hole pour in some muriatic (hydrochloric) acid and quickly fill up the hole with dirt. The gas then distributed through their labyrinth. Very effective and pretty persistent. This was Arizona so there was no soaking away. Dad impressed on us kids the danger of the stuff and would not let us near it, only watch him. We believed him and left it alone. The neighbors lost a cat that dug up a gopher and ate it.
I am old enough that during my early Navy career we were still indoctrinated on chemical warfare. The antidote for hydrogen cyanide war gas was Amyl Nitrate capsules, break them and inhale from them. Story was if we did not get our capsules out and inhaled within 1 minute we were doomed to a nasty death. Cyanide prevents the blood from releasing oxygen to organs causing rapid shut down of the system. This stuff is nothing to mess with. Cyanide was considered very persistent (up to 2 years) so areas where it was used had to be evacuated post haste. Washing with water did not get rid of it.
I read an article somewhere Congress is trying to outlaw use of cyanide for any thing except industrial processes that have no other options. A lot of folks in NV, UT, CA, and ID know first hand about this stuff as it was and still is used in the gold and silver mining and processing. A lot of mill tailings are still highly toxic today. That dark blue water in the ditches around the refineries Utah is loaded with cyanide. The blue is the give away. Prussian blue (pigment/dye) is a form of cyanide, grandpa used it in mixing paint colors.
Cyanide 101, Ron
PS, my grand kids still love grandpas stories from the old ages and call me the walking encyclopedia. Dinner time is always popular at grandpa's house.