I remember reading an article about 4 major brands of bio BBs, and how only1 brand was truely biodegradable (the rest were just BBs held together with biodegradable glue). I'll see if I can find the article again.
EDIT: Good old Arnie's http://arniesairsoft.co.uk/?filnavn=.../bio_tests.htm
Hmmm I guess that says it all. I will look into them. If I can make it cost effective for people I am wondering if they would have a problem using them.