sand safety????

Hey ya'll.  I just purchased me a 50 lb back of quikrete all purpose sand.  I didn't read the package until I got home and it was saying some jive about having chemicals that cause cancer.  I did some research and the best I can understand is that all sand has this going on.  SOOOO, I rinsed my sand really well until it was clear and then put it in my bbq to dry out.  During that whole time there was a vapor coming off that I am hoping was just steam from the wet sand.  

What exactly is going on? Is my sand off-gassing some nasty chemicals or is it just steam?  Also, what is this cancer business all about?  I am trying to make the jump to sand instead of water.  Thanks!  

Matt