Security / ODBC Drivers

We have set up every user on our system to be able to update, delete, and insert into any table in our database. Our 4GL programs have been the only interface our users have had with the database, so we have been able to control what is changed. Now we are trying to give users reporting capabilties through ODBC drivers and have not been able to restict the access to read-only. They link the tables into MS-Access and can change anything they want to!! I can't change the database permissions because the 4GL programs depend on the user and the current permissions. I need to find out if there's a way to keep the ODBC driver access read-only while keeping the 4GL access read-write. Thanks in advance for any help on this issue. Dave Killough