How safe is Orkin?

Orkin is coming to spray my home for the first time next week and I am just wondering how safe this really is? They said it's done in a way that pets can't get to anything harmful after they are done and the only time we have to leave the home (for aprrox. 3 - 4 hrs) is when they spray for flea's. I'm still a little weary of this, but really need to have my home sprayed. Any advice would be great.