I did some quick google searches and found a few interesting things about treated lumber:

Is pressure treated wood safe for docks?

A: According to a number of jurisdictions across North America, yes, it is safe to use today's pressure-treated wood for docks, rafts and other water contact structures. The pressure-treated lumber you buy today does not contain arsenic, as it did up to four years ago.Aug 16, 2008

Manufacturers of pressure treated wood reached a voluntary agreement with EPA to end the manufacture of pressure treated wood for most consumer application by December 31, 2003. EPA has indicated that some stocks of wood treated with CCA b
efore this date might still be found on shelves until mid-2004. Pressure treated wood will still be available for certain commercial applications, such as wharves and bridges, where little human contact would occur.

Sounds like in 2003 the EPA required no more CCA treated lumber.