Information from http://cetulare.ucdavis.edu/mg/articles/n032504.htm
CCA was removed from consumer markets in 2004 but can still be used for industrial purposes.
Studies have proven that most of the elements used in CCA are fixed in the wood, however some amounts of arsenic, chromium and copper is dislodged from the lumber with exposures to rain and water. The chemicals that leach from CCA-treated lumber are rapidly adsorbed by soil particles. The amount in the soil decreases rapidly with distance from the treated lumber. Vegetables grown immediately adjacent to treated wood may incorporate limited amounts of arsenic, but based on US Public Health service standards, these vegetables would still be safe for human consumption. Over time, soil adjacent to treated lumber in a raised bed garden will likely be mixed and distributed throughout the garden area, thereby diluting the effect of the arsenic that is leached.
