I recently did some bedroom remodeling to which a portion of the ceiling and some partition walls were removed. Now i'm left with a few good sized pieces of framing from my 1920s home. I was thinking of re-purposing the lumber into a planter box for my garden to grow vegetables but i'm hesitant about anything hazardous that may be in the lumber since some is original to the home. Since some was also exposed to the attic I don't know what animals/other pollutants it might have been exposed to. Tips to reuse safely?