http://www.slate.com/articles/double_x/the_kids/2015/10/sandboxes_are_full_of_germs_can_cause_parasitic_worms.html

So there I was at a kid’s birthday party, my 13-month-old daughter playing merrily with her brother in the sandbox, when she suddenly decided that she was hungry. Into her mouth it went—all of the sand—and though I was up with a leap and a “No,” I was too late. I laughed nervously while furiously fishing sand out of her mouth (it’s surprisingly hard to do, by the way) as other parents looked on with a mixture of unease and relief—Gross, but thank God it wasn’t mine. My friend, the host who owned the sandbox, appeared. “Did I ever tell you,” she said, “that I think my cat poops in there?”