they tested this crap on mythbusters..

unless you put the glass directly on a stove or some other heating element.. it's fine... keep it on it's base and it's perfectly safe...

on myth busters they proved they can be lethal if put on a stove for instance... the glass ends up shattering and shooting big shards all directions...

they tested it because ther was a guy awhile back who apparently died from his lava lamp, when a flying shard peirced his heart.