I've always read that you shouldn't store alcohol in lead crystal as it will leach lead from the crystal at unacceptable levels. It's okay to serve from a lead crystal decanter, just not to store alcohol in it.
I also have a few decanters out in the garage in a box. When my kids were young I used to set up elaborate Halloween decorations at our front door for the trick-or-treaters. (I would set them up on the morning of Halloween, and take them down that night.) One year I made a life sized witch on a frame made from chicken wire etc. I dressed her with an old lady mask, green wig, and a long black dress, pointy hat and a kitchen apron. I set up a cauldron over a fake fire, and an old cupboard full of "ingredients" which were in the old dusty decanters. I remember that year I had lost the stopper for one of the decanters, and so substituted a rubber eyeball. Of course by the end of the night that had been stolen!