Well, it could break. But most likely you would realize it before it happens. Even if you don't, most exercises do not involve a big risk -- the dumbbell would drop the weighted wheel and it would fall in the ground. If you do not have it above your head, that shouldn't do much...
Anyway, I am not responsible for anything. I hope it is useful for others, but I can't guarantee for material resistance...
Maker, Engineer, programmer/developer, Unix sysadmin, Linux enthusiast, Windows & Mac hater (proprietary software hater in general), agains copyrights and patents.