updatedb seems to ignore prunepaths environment variable

When cron runs updatedb from crontab, it ignores the environment variable PRUNEPATHS.

In /etc/profile, I have these statements:
PRUNEPATHS="/windows /tmp /var/tmp /usr/tmp /var/spool /mnt /media /proc /dev"
export PRUNEPATHS

When I echo $PRUNEPATHS, it reports back the exact same list.

When I locate files, it reports crap, for example, from the windows directories, which I am explicitly trying to avoid.

If I run updatedb from the shell command line (with no arguments), it correctly ignores the windows directory and other directories from the environment variable PRUNEPATHS.

The crontab entry has no arguments -- it is simply:
/usr/bin/updatedb

Can anybody explain what I am missing?

Thanks,

Jim
.