Marushin have news on their site of a new version of their own brand of BioTech BBs. The new 8mm BBs are 0.35g in weight (also available in 0.45g) and one would assume from the naming that they are biodegradable.
The new BBs come in bags of 500 for 1,500Yen are indeed listed as biodegradable (however we all know know that the Japanese idea of "biodegradability" may not mean what we think it means).
Apparently the brown colour is so that the BB is less obvious in a natrual environment and degrades in both sea water on normal land, however the BBs are listed as not dissolving in either water or organic solvent.
