Treated lumber chemical formulas have been changed since about 2003,
AFAIK.
Wood preservation - Wikipedia, the free encyclopedia
The CCA is no longer permitted for residential use(box store customers) and
I think they use a copper-based chemical called ACQ to coat the outside but not cut ends.
Sill plate should be made of this at a minimum with some kind of barrier underneath to keep moisture from wicking up. Any wood next to ground or concrete will act like a sponge.