I am not an expert on the treated wood but here goes...in years past wood was treated to a standard or .40 or .45. Pressure treated wood was a darker shade back then. It is now treated to a standard of .25 or so. It should be stamped on the wood. Now it almost takes a second glance to see if it is pressure treated or just plain lumber. Cheaper,cheaper,cheaper. As far as the carcinogen there are some facts there. School playgrounds can no longer have pressure treated wood structures here in NC. They are being removed and replaced as of 2011. We did a fundraiser and had a wood jungle gym built at my son's elementary school in 2009. In 2010 it was torn down and another fundraiser for a powder coated metal structure.
I will try to get pics of mine but I do not have that capability with my phone. The next time my son and I have a day off together I will post them from his phone. My pen is made with the wire to the inside of the posts vs. the outside. My end panel is a door with the wire to the inside. This keeps the chewers off the wood for their benefit as well as the longevity of the pen. EWO