Here is an entirely unsurprising story about the Large Hadron Collider (LHC) from the Beeb. Guess what? Apparently, it's perfectly safe, and they're to be allowed to switch it on.
A good rule of thumb for the conspiracy-minded and half-witted for future similar situations: physicists are neither stupid nor terracidal. No one is going to rush to build something which, on the off chance, might happen to... oh, let's say destroy the planet. Because, at the end of the day, even if you have found the Higgs boson, if you can't write up your paper on your notebook over a mochachino in the café afterwards, it's not going to do you a hell of a lot of good.
Yet another sign, in short, that we need to do a better job of educating and communicating about science.