Oracle Database Discussions

Hi,

My question is - Is there anyway to find out when a tablespace/datafiles was last used?
I have searched and I think the answer is no but I'd appreicate any ideas.

The issue we have is that is seems very difficult to get users to housekeep in my organisation.
Employees leave the company but in my company a developer MAY pick up someone else's tablespaces (to save them from a new installation).
So we cannot assume that just person A has left the company that their tablespace/datafiles are usued.
There is no simple way to verify apart from getting positive confmation from every developer in the company.

So is there anyway to establish this in Oracle?
If this could be done then we could drop any datafiles/tablespaces that haven't been accessed for X years.

Thanks
Lisa