Treated wood for a childs sand box?

My Father in law is making a sand box for my son with lumber treated with Copper Azole CA-B. I have looked at websites that give information on it, but I haven't found an answer that relates directly to sand boxes. My concern is if the chemical will leach into the sand and if it is harmful to a young child that will most likely live in it with his trucks and tractors. Any help would be appreciated.