MAC web browsing

Dealing with a MAC (MAC OSX v 10.3.3 Panther). I have a number of entries in a cache file at location ~/Library/Safari/Icons/. Some of these entries are interesting as they appear to be incriminating Google search terms. Safari is the web browser being used, and I am aware that this location is a cache for 'favicons'. Anyone know why Google search terms would be captured in this cache file. And/or what exactly is this cache file all about?

Andy