this is actually sodium cyanide(NaCn) most likely. its made from sodium hydroxide(caustic) and hydrgen cyanide. hydrogen cyanide is extremely dangerous, a couple of drops on your skin or inhalation or ingestion will most likely kill you in a few minutes if an antidote is not administered immediately.
hydrogen cyanide is a vapor under atmospheric conditions(above 60F i think). but this product that was stolen is in solid form, similar to a piece of charcol but white in color. it can be a problem if dumped into a riverway or city water system. it dissolves in water and will release the cyanide, but it isnt that deadly under that condition, unless you were to do it in a closed space of some kind. it just doesnt release fast enough. it releases faster the hotter the water it is dissolved in. i use to hose it down all the time with no problems except for the poor pigeons that would drink the sodium cyanide laced water. hehe. we make this product where i work and it is shipped and sold under Dupont. we actually use to ship it to mexico daily. the unit has been down for a year so i think this probably came from duponts tenneessee plant. just some info.