People come up with some really weird ideas on gun powder, especially smokeless powder. Unless you are a pure idiot and are going to do something stupid, it's not dangerous, it won't detonate, but it will deteriorate, which makes it not suitable to shoot, not because of danger of blowing up, the cartridges won't be accurate, and like others have said, there could be hang fires or duds. But that all takes place inside a gun, not sitting on a shelf. Old powder can be disposed of by burning. Once outside of a container, it won't blow up, it just burns. Of course it burns fast and will start fires, so one must be careful, but there will be no explosion. Many will probably be surprised to find out that ping pong balls are basically gun powder. Ping Pong balls are made of celluloid, which is like gun cotton or nitrocellulose, which is extremely flammable and is the basis of modern smokeless gun powder. Don't believe me, find a safe place and light a ping pong ball on fire. What I'm trying to point out is that ping pong balls get whacked back and forth and don't explode any more than a loaded cartridge would if dropped or bumped into something. And the brass doesn't get brittle just sitting around. It gets brittle from use, when fired it expands, then is resized, loaded, fired, and then expands again and is resized, and this is done a number of times, causing the brass to become brittle and crack, but all you have to do it anneal the brass, and you are good to go again. The deterioration of old brass in the ground is caused by water and salts in the black powder residue, and on load cartridges there is sometimes electrolysis between the lead and brass. After smokeless powder was introduced I think the salts from corrosive primers also caused some brass to deteriorate. But on empties I've found that are from after the Korean War when the military started using non corrosive primers, the cases seem to last in the ground just like other brass. Sitting on a dry shelf in the house that won't happen. I have a collection of old cartridges, found, dug, purchased etc., some loaded during the civil war, some in the 1870's to 1900, a few from WWI, and all the way up to now, and they just sit there on the shelf and smile back at me.