Do any of you guys replace your EDC pepper spray canisters on any sort of a regular basis? My wife and I each carry a can of Foxlabs that I bought over a year ago. I don't know how old I should let it get and still consider it reliable. I'm reluctant to test it out in my back yard. On another note, what would be the best way to dispose of old canisters? I certainly can't imagine just chucking a full can of pepper spray in the trash can.