Momma Cluck, I don't think you should worry, but I would suggest that whether or not you use DE, having the brooder in the house or wherever creates a lot of dust. So, it's probably best to keep the brooder in a basement or a barn if possible. I did have mine in a bathroom, used no DE, just pine shavings, and boy was there dust! they scratch and stir it up all the time - pine shavings and dried poop!
Too much dust isn't good for any of us. I have heard/read that even when sprinkling DE, be careful not to inhale too much.
DE is a naturally forming mineral/substance, so I don't know about hazzardous. Though I'd not be surprised if the tiny particles could cause irritation to our lungs.
REmove the brooder from her room, Open the windows and air it out, dust well, stop using DE until they are living outside, and when using, do it sparingly and with a mask on ...or carefully upwind from the sprinkling.
All the best.
(I'm not using DE in the bedding). I remember the same thing from the first time I had chicks. I figure that my kitchen is going to get a major spring cleaning
