php permissions

php is running on our box as nobody:nogroup. I'm trying to write php code that will edit/delete files uploaded to the server by other users, and, obviously, I get a permissions error. My sysadmin is hesitant to give php more access until I do some research about the security issues involved, and I am a relative newbie and I'm not sure what the issues are or how to find out more about them. How do I give php permissions to delete files etc., without opening up an security hole? Is this an issue at all? Help! Thanks!