What are the threats in giving a freelancer your Facebook/Twitter dev keys?

Hey guys, I'm looking to have a freelancer help me with some RoR development and I currently have my facebook/twitter dev keys in an initializer. I figure that I can remove my keys and then reset them and have a developer use his own, but I was wondering what the risk was if I just let him use my keys?

Is there a better way of handling the keys so that their private?

Thanks