Yes, reptile sand is safe for chicks! The only reason I used play sand at all is because it was SO dirt cheap in comparison to the tiny little bags of expensive reptile sand, lol. I much preferred the reptile sand, so much easier to scoop with no big rocks like the play sand has.
missnu01 - I put my goslings on pine shavings rather than sand for that very reason. They get their area so nasty so fast that it's nicer to just clean it all out! But since chickens are much more dry, I find it works great for them... just not waterfowl, in my experience!
I'm glad this thread is still helping people.