Hey there, DB,
Check out their manufacturer:
http://bioshotbb.com/
These are regular "biodegradable" corn plastic BB's, which technically require industrial composting conditions to degrade.
True field testing would be needed. Though someone tried at:
http://www.airsoftforum.com/board/Bi...w-t181630.html. He achieved moisture-based degradation in 10 days of continuous submersion.