Sorry, it's a mulch and not a substrate. My fingers were getting ahead of my brain plus I was on my phone. I've found one other link talking about it in reference to reptiles (and not just cats/dogs) but it is almost a decade old at this point. I haven't bought any yet, just because what I going to do with a $9 bag of mulch if I don't use it? We have dogs and while I wouldn't worry about it being in a tub away from where they can get to it, it out in the yard where they can get to it is worrying. I can go out tomorrow and take pictures of the bag but I already read it and there wasn't much on it that was very helpful.