But what about growing veggies? What are the chances that toxins could
get into the vegetables from the lumber if it's treated? Has someone
actually tested to see if arsenic leaches out and gets taken into the
plants?


My ten-year-old raised beds are constructed of approximataely
twenty-year-old CCA-treated "landscaping" timbers of the type you
describe and my dain bramage is hardly noticeable! Typically, such
timbers are dipped but not pressure treated; treated timbers will bear a
tag indicating depth of penetraton. Of course, some portion of the
arsenic leaches into the soil and _may_ (under specific circumstances)
be taken up by vegetables -- root vegetables and potatoes, in
particular. Arsenic also occurs naturally in soil and is taken up by
veggies. Outside of an agenda-driven popular press, I have not seen a
single study definitively establishing a link to human health at the
concentrations commonly found. Moderatly-priced soil testing kits exist
for the consumer market. The issue of arsenic in garden vegetables is
not at all related to that of transference of arsenic from new,
unweathered CCA-pressure-treated wood onto the hands and into the mouths
of children from treated wood playground equipment.
Bear in mind that neither reason nor empericism has a place among
the agenda of the world-changers who depend on strident and persistent
FUD to spread their views and to bludgeon society at large into
acquiescing. While they may be useful for studying gardening techniques,
skills and old-timey lore, I suggest that you view with skepticism
"studies" cited in popular publications with "Organic", "Green" or
"Mother" in their names: Their POV is implicit and any "conclusions" not
to be trusted. You may find this document from the Penn State College of
Agricultural Sciences of some help in making your decision:

http://pubs.cas.psu.edu/freepubs/pdfs/uc173.pdf

I direct your attention to the beneficent effects of high levels of
organic matter/compost in garden soil and of simply peeling root crops.


All that said - and thank you for saying it.
I used cedar for my food-raised beds.
and for the touchy-parts of the kids play centre.
Green-Treated wood for the rest.
Calculate the cost difference - in my case - not much.
Peace-Of-Mind ... priceless.
John T.