In new construction to outgas volatile chemicals they run the heat up to
about 120 degrees F for a weekend. This removes the majority of funny gases
from carpets, paint, particleboards , glues , resins and such.
  If you were to leave your frames in a warm spot for a while (In the hot
sun) you would outgas most of anything left in the wood.
  Perhaps one of our list members with access to a gas chromatograph could
put a few samples of plywood in a jar and see what outgasses.
  I bet the APA (American Plywood Association) has facts and figures on file
somewhere.