Tor in and of itself can present a potential for a security hazard. This mainly has to do with the fact that the end node does not establish an encrypted or otherwise secure link with its end destination. While the other 4 hops are "dumb" to the information that's being submitted and where it's going, this creates a security potential for the end node to begin sniffing for information.
My recommendation here is not to use any personal information when making use of Tor if you so choose to use it. This caution comes from the hands of someone who has had much experience with this type of thing. It happens more often than you might expect.