Yes, there is accepted evidence of this. Blasting sand, paver sand, and similar are not refined beyond the crushing up. They are intended as binders, blasting, etc, and sharp particles do these functions better. When |I was considering sand 7 or 8 years ago I contacted Quikrete about the processing of their sands, and this was clearly explained to me. Play Sand they said is the most refined sand they produce because it has to be free of any angular/sharp edges. This processing achieves much of what is achieved with natural sand in a river, which is why "aquarium river sand" is recommended by the catfish experts. But aquarium river sands are very expensive. A bag of Quikrete Play Sand at my Canadian HD is under $7.
Play sand is safe, it is after all processed for kids who get it in their eyes, mouth, swallow it...it is safe. I've had it for 7+ years now. I get mine from Home Depot; Lowe's also carry it. They have the dark grey mix at HD here, but apparently some stores have this and others the tan. Check with your local HD, they carry Quikrete Play Sand, you might find the grey locally. It really is a lovely substrate.