I've been using river sand as grit for my chicks for years without any problems. River sand is not as fine as playground sand, the grains of sand range in size from fine to large and it is more course. I put it in my coop as bedding last year, also.
On the old timer thread, they recommend river sand for chickens as grit. So, I'm skeptical about it being dangerous in any way for chickens.
I agree. Free Range chickens don't even need grit. The rocks stay in the gizzard to grind up the grain, so they need to be sharp too.
Ron
