At Marks-Miller Post and Pole, Inc. we use Osmose brand Chromated Copper Arsenate wood preservative, commonly refered to as "CCA".  CCA preservative has been a proven wood preservative for many years.  CCA was developed in 1933 and has been used extensively since the early 1970's.  Beginning January of 2004, the Environmental Protection Agency agreed to chemical registrants requests to place "use restrictions" on CCA treated products.  Generally, CCA treated products are allowed to be used in agricultural and highway applications only.  Most residential applications are resricted.  For more specific information about CCA product uses, click on the following website links.