I used to haul directly from 2 plants, 4 years worth of keeping the yard stocked with CCA treated lumber, the vessel is impressive, as is the process.
The EPA has quite a bit of information on CCA and I don't know, but I think a lot of this came from Picnic tables and them using it in school yard playgrounds, + Arsenic, but the material did perform well, now they treat it like lead paint.
Osmose, I believe still makes CCA treated wood and the EPA does have a list of approved uses, I do believe you can order it, some of the uses are utility poles, agricultural fences, not sure if they list pole barns or ag buildings, I did post links quite some time ago, its on the web. Osmose link below does have a link to the EPA site. The next link is interesting reading, CCA works fine and is safe when used properly, its just people that are ignorant.