Depends on the type of treatment it had and how old or how new the wood is. Only the manufacturer can provide that info.

Some treated wood made prior to 2003 contained arsenic in the process. Wood treated since them does not and is rated as safe. Older wood that has been in place for many years will have already leached most of it out into the soil. Some studies show that working large amounts of good compost into the soil can neutralized any chemicals remaining in the soil.

Basically it boils down to your choice. Some are really concerned about it, many are not.

Dave

Here are a number of previous discussions on this question that you may want to browse through.

Here is a link that might be useful: Pressure treated wood discussions

Thank you!

I would also be concerned that the house was treated for termites. I never plant any edibles around the perimeter of my house for this reason. The termite companies even recommend not doing this. They say don't even have any plants that birds will eat (such as holly berries) within 5' of the house because it can kill them! I'm trying to figure out if the fence is safe. If not, both my side yards are no edible zones, unless it's in pots. The back yard isn't much better as it's not very deep. There is just a small strip of yard in the middle that would be safe.

I wonder if even fruit trees are okay? I have a peach tree & a mulberry tree next to my wooden fence. Does anyone know? Also, would it be okay to plant cucumbers, squash, etc a couple of feet away and train them to grow up the fence?

I did some reading on this recently. In a quick cruise of my bookmarks I don't see the links (I can look again when less tired), but basically what I found was that studies show tree fruits do not put much of the copper and arsenic from treated wood into their fruits, although it shows up in other parts of the tree. The fruit is pretty safe.

(The study was on particular varieties of apricots and apples, and the guess is that this is true for other fruits as well.)

Vegetables that you eat the roots and leaves of, OTOH, are more problematic. Especially roots.

Near houses and roads, lead is an issue. It is not recommended that you plant leafy vegetables there -- or, if you do, wash them very thoroughly. A lot of the lead is in surface dust on plant leaves, and on the dirt on root vegies, rather than in the tissues of the plants, so you can wash it off.

You might consider raised beds... if you know the history of the dirt you would be importing.