I thought Coke actually did have cocaine in it a hundred years ago or so, and pulled it when it became obvious how dangerous the stuff was.
On the topic of other top secret material, however.... Hmmm... I hate to say it, but I think things like nuclear launch codes, code books and other secure materials might get "picked up" by the Library's magic; however, stuff like that is almost certainly kept in the Restricted Shelves in Administration. If nothing else, the gods in charge of the place realize how dangerous that information is and keep it out of the main shelves. (which reminds me: I'm not too familiar with Japanese mythology, but is there a god or kami in charge of knowledge? He or she (or it) would almost certainly be on the Library's deific coalition).