For square foot gardening, I was thinking it might be cheaper to use landscaping timbers that have two flat sides, drill holes near the ends with two of them stacked, and then drive 1 in. EMT conduit into the holes to fix them into position---- like I have seen done with raised flowerbeds. Untreated wood would probably rot in a short time. But what about growing veggies? What are the chances that toxins could get into the vegetables from the lumber if it's treated? Has someone actually tested to see if arsenic leaches out and gets taken into the plants?