I must agree and disagree with gdolby. I have been reloading with some old surplus 4831 with no problem at all. WWII 4895 has a history of problems. I have been reloading PB, 700x, and Red Dot for years with no problem in both handgun rounds and shotgun. One of the key items is that you are able to identify the powder. The next is to find the appropriate data for the powder and cartridge you want to load for. As suggested try manufactures websites, buy a manual or two, go to the library and you might find a manual. Manuals do not list all powders so you might need more then one. These manual may have a section on checking powder.
Currently I am in process of disposing of some (good) old powder. I have loaded a number of rounds to practice with before deer season. In my case that is how I am going to dispose of the old powder. I have been reloading with surpluse 4831 for close to 40 years with no problem.
"Powder deterioration can be checked by opening the can the container and smelling the contents. Powder undergoing deterioration has an irritating acidic odor. (Don"t confuse this with common solvent odors such as alcohol, ether and acetone.)* Also a red dust or sticky substance may be present." There are other recommendations. One is in line with gdolby recommendation. *25 Edition Powder Data Manual Hodgdon Modern Smokeless Powders.
Like you am concerned about the safety and storage of the powder that I own. I do check it, and if I find some that appears to have a problem I will dispose of it in a recommended manner.
There was a problem with a bunch of WWII surplus 4895. I have a friend who's family of 30-06 shooters purchased a lot of it very cheaply. It went bad and they had to dispose of it. I brother loads a truck load of current 4895 without any problems. It never has a chance to go bad.
I was given PB and 700X by a family member and used it to reload pistol rounds for target practise. I loaded to manual recommend standards and had some enjoyable time at the range.
If you are in doubt dispose of it.