You can also use the she bangs (!#) for manipulation the enviroment. For example assume you want to create a particular enviroment for you script if you use

#!/usr/bin/perl
foreach (keys %ENV){
   print $_ . " " . $ENV{$_}."\n";
}
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You obtain the enviroment from which you run the script.
If you use:

#!/usr/bin/env -i perl
foreach (keys %ENV){
   print $_ . " " . $ENV{$_}."\n";
}
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You obtain nothing.
see info coreutils env