There was an article/essay in Organic Gardening in 1993 or early 1994 (I think)
concerning using treated wood near gardens and as playground equipment. The
essay criticized a news release by a member of the Texas Agricultural Extension
Service that claimed that there was no harm, and then went on to cite a couple
of major studies that showed definite leaching effects and uptake, especially by
root crops. The studies are cited in the article.
I have the article at home somewhere in a stack of magazines in need of
organizing, and will attempt to find it this weekend. However, an electronic
library search might find it quicker.
Agricultural Engineering Department
Texas A&M University
College Station, TX 77843