I have used oriented strand board (OSB) in making inner covers.  I find
that the major problem is that when propolis or beeswax fastens the
cover to underlying structures the strands pull off and separate from
the board.  Because of this I find it of limited usefulness.  I doubt
that the glues used would interfere with the bees or get into edible
products, since the board seems to be rapidly covered with a propolis
varnish, as is every other hive surface.
 
Ted Fischer
Dexter, Michigan USA