They still use the arsenate version but it's pretty much restricted to industrial uses like guard rails and trestles. It WILL leach, but the amount is small and the amount that even the hard core anti-chemical people (like me) say that could possibly be "taken up" by a plant and put into the edible bits is a tiny fraction of that fraction. It all boils down to where you draw the line in the sand, but I doubt, if you hire a whiz who owns a mass spectrometer, that you could find any amount of chrome, or copper, or arsenic in your garden food that is in any way different than normal God-given background amounts. But avoiding poisons in your food is a whole rigor, not an individual chemical thing. There are people here who dump poisons on their crops and say it's just fine. It's all up to you.

If you wait that long a time period, PT lumber exposed flat to the Sun will split/crack/ warp and generally through a fit like a two year old. If a man waits 6 months or longer the wood will have opened up to the point it will suck up 3 times the finish. I use TWP 100 series outdoor finish there is no bubble peal goes on with it, ever. PT decking / lumber will take that finish or any other just fine fresh out of the lumber yard. If you are that so far out of date to not use google or any other search engine for info I cant help you old timer. The quicker the finish is put on the more protection the wood will get. But it hardly matters with PT decking because with or without finish it will generally do the same thing exposed to the Sun.

@Gardengal - that's dimensional lumber for construction. Fine for posts and rails - no decking or pickets however. Also that place caters to contractors. I can't remember which place it was, but when I first got here about 4 years ago I went to a lumberyard that catered to contractors and was unceremoniously asked to leave as they didn't want to bother with folks buying anything less than pallet-loads of lumber. So I have not tried any other "professional" lumberyards. But I guess I may have to risk it again. @Ryan - see above. Also I don't know who/where they are, if they're not on yelp or they don't turn up in a websearch. If I put in "lumberyard" I get all sorts of places where they clearly want to sell a truckload at a time, and don't list pickets or decking but only dimensional lumber (if they list anything at all). I'm disabled and waaaay out of town so driving around looking (only to get thrown out the one time I physically went to one of these places, and I cannot for the life of me remember where it was) is a major undertaking for me. If I put in "fence supply" or "fencing supply" I get all sorts of hits on places that are installers, not suppliers. I'm still looking - but I'd really like to know why HD and Lowe's are not carrying what I need. You may poo-poo big box stores, but those of us who are not contractors and don't buy things in job lots are at a disadvantage much of anywhere else. So is anyone ELSE having trouble finding pressure treated fence pickets and decking? Or is it just us here in Nevada for some dog-forsaken reason? Or is there a secret lumber supply place where we can get it (for reasonable prices) if we do the secret knock, know the password, and can perform the secret handshake? LOL!

I have used Olympic deck stain (semi transparent) on several pressure treated decks. It works fine. However, you are not supposed to do anything to a pressure treated deck for a while. It used to be 6 months, until staining, but, a friend told me, she was told 8 weeks, unless there had been a lot of rain, and then to wait a bit longer.