I would too without a second thought. We tend to forget that even way back when the CCA issue was at its peak and was not recommended for gardens, the recommended spacing between the boards and the produce when it was used was only 6". 17 year old boards are no problem IMO. Dave

It's advised to not use PT wood because there are safer alternatives. That said, the stuff isn't a deal breaker for your garden. Once built the biggest real danger is putting your hands all over the stuff while harvesting...contact stuff. There isn't much to leach into the fruits even in the most toxic of PT lumbers. Plants generally don't pass on much soil toxins because they have no use for their uptake and very little makes it to the actual fruits. Like the above poster said...if you bought your PT lumber recently there's an even larger chance that it's the safer stuff. A lot of the issues with old PT lumber involved people putting their hands all over the stuff or laying produce on it to rest. Even then, a good washing takes care of most all of that. It's the arsenic in the wood that was a huge issue with the last generation PT wood and how you could accumulate arsenic levels on skins just by rubbing your hands across it. A lot of the "panic" came from how much PT lumber is used in kid's playground equipment.

Henry, I don't see a photo of a raised bed on that link. I'm wondering why the recommendation for cedar? When wood breaks down when used for a raised bed, it is from contact with the soil, not from pests, that cedar would offer protection for. Cedar is more expensive, that is why I ask. I've always used the cheapest wood I can find. I tried cement blocks once and after two seasons, I broke down that bed and went back to wood. I found the blocks heated up the soil more than wood.

Ok, here's a crude calculation just to give you an order of magnitude. Let's suppose you had 10 lb of ash, and it was dug into a 5x5 ft area to a depth of 1 ft. While searching for the actual formula of CCA, I ran across a paper on the metals content of CCA treated wood ash, so I could skip some steps. CCA was made in two grades, 0.25 lb CCA/cu ft of wood and a higher grade 0.4 lb/cu ft. Their sample was 4 kg/m3 which works out to about the 0.4 type. The ash was about 20,000 mg/kg (ppm) Cr, 10,000 ppm Cu and 11,000 As. After a bunch of conversion, that comes out to 36 ppm of additional arsenic added to the 5x5 area if distributed a foot deep (using 1.5 tons/cu yd of soil). I picked As because it's the most toxic of the three metals. Now this is above health-based guidelines for residential soil, which are in the range of 5-15 ppm. Note, those numbers are based on your entire yard being at that level, and living on it for a very long time, with a resulting risk of death from cancer or non-cancer health effects reduced to essentially nothing amongst all the noise of other risks in life (i.e. a rate of 1 in 100,000 or 1 in 1,000,000 excess deaths). You will not experience arsenic poisoning from this soil in the way that you're thinking. It's more like a small incremental increase in health risk, much like smoking a cigarrette (or a whole pack ) won't kill you, but it's not particularly good for you. Here is a link that might be useful: CCA Ash Analysis Paper This post was edited by toxcrusadr on Wed, Nov 20, 13 at 12:00