The LHC safety report (http://public.web.cern.ch/public/en/LHC/Safety-en.html) makes the good point that whatever LHC will do, Nature has already been doing for billions of years. Cosmic ray collisions have far higher energy, and over the lifetime of the Earth, about a million LHC lifetimes of interactions have taken place. Si if the Universe should be destroyed, Nature should have taken care of that by itself a long time ago.