In the past year we have completed a couple of projects for our backyard that we needed lumber for. For me it was a no brainer in choosing the appropriate wood, CEDAR. Cedar is not chemically treated, but is resistant to bugs and decay. As you may assume, cedar is also more expensive at your local big box hardware store, but to me what price would we pay for exposing ourselves to toxins in pressure treated wood, to save a few bucks? So, it's certainly worth about $4 more a board to protect our health.
In years past, arsenic was used in pressure treated lumber, which has been listed as a known carcinogen by the Environmental Protection Agency. Around 2003 the arsenic in pressure treated lumber started to be phased out due to it's toxicity to humans. Simply google Toxins Pressure Treated Lumber and Lawyer's websites are the first to appear, which is highly indicative of Class Action Lawsuits. Chemicals (amine copper quat (ACQ) and copper azone-CA) are still used to treat wood today against rot and insects, in pressure treated lumber. There are many applications where pressure treated lumber is fine to get the job done, but when my children are involved and susceptible to exposure to these toxins, I prefer the alternative.
What to do if you have Pressure Treated Lumber in your playset or deck?
First you can test for arsenic, if it is found in your playset or deck one alternative to removing the structure is staining it with a solid stain. Clear oil based sealants weren't found effective against creating a barrier within a few months, in tests by the Environmental Working Group.
EPA LINK to alternatives to pressure treated lumber.
2 Backyard Projects, where we chose Cedar over pressure treated lumber:
Our Sandbox, which has been the first choice to endless hours of backyard play. The girls rarely handle the wood, by why take a chance?
This year we built our raised garden bed. I spent about $20 more for Cedar, than I would have with pressure treated lumber. Obviously for growing vegetables (organically) I am not going to house them in toxic chemically treated wood. Please do not use Railroad ties (toxic creosote) or pressure treated lumber (unsure of chemical impact), follow these directions!