As of December 31, 2003 CCA (chromated copper arsenate) wood treated products have been banned for most applications. You would have trouble finding it anymore. The most commonly found alternatives on the market use ACQ treatments (quaternary ammonium compound). These do not have the long term health effects associated with arsenic. The drawback of ACQ has been it corrosive effect on metal fasteners. In spite of concerns about the chemicals in treated lumber, even the ACQ is not a known problem for human health exposure after it has dried, and provided you are not exposed to respirable sander and sawdust.

For a childrens play-set, there is really no good reason to use treated lumber at all. I recommend treated lumber only for the material in ground contact (support members). The rest of the unit can be built from dimensional pine, douglass fir or redwood. These materials will finish nicer and not produce the splinters which are a major problem with treated lumber as it dries and shrinks from the treatment process. The life of untreated wood products, properly stained with an oil base stain is plenty long enough to outlast your children. You are much better off to consider conventioal framing or deck finishing lumber for this project.

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