environment variables

Hi all,

I'm not quite sure what environment variables are set when executing
an interactive screen vs. a detached screen. For example, when filling
in this

$ cat ~/.bashrc | grep FOO
export FOO="bar"

I get

$ screen
--> screen
$ echo $FOO
bar

but a detached shell yields nothing:

$ screen -s /bin/bash -L -d -m echo $FOO
$

Any idea why this could be?

Cheers,
Nico