Specialized microorganisms which are able to convert fixed inorganic preservatives from treated wood into water soluble components are investigated. A number of brown rot fungi like Antrodia vaillantii have been isolated from cases of damage and examined under unsterile conditions with CCA-, CCB-, CCF- and CC-treated wood at retention levels of at least 50% higher than recommended for wood in ground contact. Depending on the kind of fungus, preservative retention, wood particle size, culture conditions and duration Cr and As can be almost completely leached from the treated wood. Cu reacts with oxalic acid to a compound of limited water solubility.