I haven't used them. However I am on their mailing list, and just got notified of a blowout sale on their organic tees for kids a couple days ago. Kids styles 511A (boys SS basic), 511B (boys SS euro) and 621A (girls LS basic).
As for the carbon footprint question, if you don't hear back from a forum member, you might call or email them. Contact info is at:
Contact - Article.1