Is it safe to use treated wood for raised bed gardens?
The answer to that question used to be a solid "no", but I recently came across this post by The Natural Handyman who says the old chemicals used before are not in use now. And it's safe to use pressure treated lumber.
The Natural Handyman says: until 2003, the most common preservative used for pressure treated wood was chromated copper arsenate (CCA), a compound using arsenic as its primary rot protectant. Over years, the industry, in cooperation with government recommendations, phased out the use of CCA for all residential and most commercial wood pressure treatment. Part of the reason was the fear that the arsenic would poison the soil and anyone who touched it. Though actual cases of poisoning via pressure treated wood use by the public were hard to find, there was enough circumstantial evidence of soil contamination to warrant a change.
Here is the rest of the post: