In order to get a proper understanding of the safety of using treated pine, this ingestion information must be taken in turn with the idea that the overwhelming majority of the treatment will be locked into the timber chemically for the extent of it’s life and will likely go nowhere. Having said this, it’s also prudent to point out that a very small amount of leaching can occur from the timber. This potentially poses a small danger to soil close to posts sunk inground. The leaching has been shown in studies to affect the 100mm surrounding each post. These studies showed that root crops grown next to CCA treated posts inground showed a small amount of coughnic content (which was determined to be in a safe organic form, and could be removed by peeling) If you are concerned, this leaching issue can be averted by either not growing anything within 100mm of a sunk post, lining your garden’s perimeter with a gardening plastic, or mounting all of your posts on post shoes which will lift them aboveground and prevent any leaching whatsoever. Softwoods mount all of our posts on post shoes (except occasionally with internal posts for decking)