Playground sand causes what???????????

Ryan picked up some playground sand from the store to refill our sandbox because over the years our sand had "disappeared". Imagine, to my dismay, I found out that the State of California has put out a warning on the sand stating that it can cause cancer. My sister Lori told me this and had me check the bag to see if we had purchased this type of sand. Guess what? We had. So, I googled the topic and found that the ingredient that causes cancer is crystalline Silica. (That may be spelled wrong.) Now, this has been around for many years and we all played in sand sooooo what to do??????? I thought over this for 24 hours and just cannot get comfortable with knowingly exposing my children to this harmful ingredient. So, we will be dumping out the sand and purchasing another type. (I have to ask Lori what it is and where to get it.) Now, at M's preschool they have a huge sandbox filled with sand and it is covered so animals cannot get into it which is great. But, what about the sand that is in it? I know that many things can be linked to cancer so am I just being too intense? I chatted with my friends about this, and they too are concerned with the sand. So, to all of you who have sandbox loving kids, watch out!