I would be concerned with toxicity if the cardboard had any ink about it. If it holds a lot of moisture it could possibly bring forth mold problems too. I've seen there is an Arm & Hammer natural pet bedding now on the market which is made from cellulose fibers. It also contains their odor absorbing baking soda. I'm still in debate about using this type of bedding in a baby chick brooder. We bought several bags of this because it was for sale at a greatly reduced price at an Amish discount store. So, needless to say I have LOTS of bags of this. I'll do a review if we ever decide to use it at Red Barn Farms. The first thing I noticed was the large size of the bedding. It's not small ground by any means.
