Actually OP was referring to safe sand as in the brand but really any sand that is free of tremolite (a form of asbestos) and crystalline silica. Crushed quarry rock being the most dangerous. Most play sand is not labeled as to its source so you really have to call the manufacturer and specifically ask.
I called everywhere last year thinking finding beach sand would not be difficult in the Seacoast NH region to find. I was wrong! I did finally settle on a brand after talking to the company that sells it and the company that makes it. I can't remember the name of the brand but I would be happy to check our shed as I think we still have another bag in there. I know we bought it locally but it might be available elsewhere in New England. Feel free to PM me if you want me to check.