Can I restrict backups?

Hi,
now this might be a bit of a silly question, but I'll give it a shot anyway.

I'm working on a remote database for a few employees of a rather small
startup company where at least a few will get teleworking jobs. They'll
get a ms-access application that connects via ODBC from their home.

They'll have limited access to the tables. Some will be just readable or
writable.
Obviously to work with the most intersting data they'll need reading an
writing access.

Could I somehow avoid that one of them uses pg_dump or even Access
itself to pull all the data out and sell it to a competitor?