More info!
Okay, so silica sand is not good to breathe in, blah blah blah and all that. Not saying it's not important, but you get the gist.
http://www.lbsilicasand.co.uk/silica-sand-equestrian.php
So silica sand is used in equestrian sports. When I think of it being used in an arena, I think of a /lot/ of sand getting kicked around. Yeah, and it says that silica isn't the best for bedding, but...
http://ezinearticles.com/?Silica-Cat-Litter---A-Wise-Or-Unhealthy-Choice?&id=935852
Yep, eating silica sand is bad for you. Chickens + sand/rock/grit = chickens eat sand/rock/grit. Not good.
Found this on BYH:
"Emmetts Dairy is right on the head with this stuff. I have to work with it at work occasionally and I wear PPE when using it to avoid the dust and contact. They EPA is currently trying to reclassify it as a hazardous material, so I would avoid it like the plague. I am hoping they do because I hate testing it. Also, if you use sand, make sure you use play sand and not silica sand. Silica sand is very bad for the lungs. I test soils and concrete for structural strength and physical properties for a living, so I get lots of info on stuff like this."
So I guess this means silica isn't the best choice.
I'm not even sure if my sand /is/ silica, but I think it is.