use log_statement to log only SELECTs?

Hi,

I've been looking for a way to use log_statement to log only select
statements; is this possible?  (I'm using PostgreSQL 8.1.18)

I'd like to know if someone tried to read the data back from the
database, but don't care to see the inserts or updates since these may
have sensitive data like credit card data which I don't want logged in
the logs.  I really don't even care if the SELECT was successful or not,
or what the results of the SELECT were.

Thanks,
Brian