Um, Please tell me that you are shooting those from far away, not to sound like a lawyer, I can understand shooting the tin disposable helium tanks, but, the propane, and the tank, is literally a bomb if you set it off, and unlike tannerite, contained in a thin plastic bottle, there are Large Chunks OF METAL flying around, and it may be 'safe' for you but not the guy over a little ways.
Point is, I really don't care what you shoot,(as long as you pick up after yourself, please)
But don't be stupid and kill or maim someone, or yourself.