Hmmm, I guess my chickens didn't read that chapter in the book....they've been on shavings since day one. The first couple of days I covered them with paper towels until I knew that they were eating well, and yep, they ate a few bits until they figured out that food was in the big container with the holes in it and poop was in the shavings, but all are hale and hardy. I think it's misleading to make a generalized statement like "Pine and Cedar Shavings ARE Dangerous" when simply saying that they "Might" be dangerous would have been more accurate. No one disputes that shavings might be eaten by very young chicks with detrimental effects. They'll also eat anything else that finds it's way into the brooder with the same outcome. New chicken owners have enough to worry about (Am I doing this right? Are they warm enough or too warm? Why are they doing that? What did I do wrong?) without being scared of yet another issue with a slight - slight - potential for problems. When I got my chicks I found a million ways to give myself a guilt complex - not doing that again.
You may find my research interesting [*CLICK*] but yes, they "are" dangerous, though how much so to your particular flock is way, way up in the air. It depends on the other conditions the chicks are in, how healthy they are, how much they breathe, etc. etc. Some will seem just fine with the effects while others develop serious health issues, just like humans when exposed to second hand smoke. It's not a clear-cut never-safe-to-use product, but I think it is good for owners - new and old - to understand the potential hazards.