I've done some research on the ingredient mainly used called sodium bentonite and so far all i've turned up is that it may cause him to dehydrate. Does anyone else have some information that may be useful?
~Worried~

Can I ask why you're training a puppy to litter and not to outside?

I really don't think you have anything to worry about, obviously don't let him eat it, but, I think its fine.

My I.G. is puppy pad trained and he does pretty good, sometimes he misses the mark but I put them down in the bathroom that has vinyl flooring so its an easy clean up. He is trained to pads because I live alone and sometimes am gone for the day and its better for him to just use a pad than to spend TOO long in a crate. I do not have anyone to let him out if I need to be gone overnite which is not very often but does happen sometimes. Also, mine is an Italian Greyhound which the breed hates going out in bad weather. I had looked into the litter and even had a pan but Tater would never go in the middle, he would stand half in and half out and it would just go EVERYWHERE. So now I just put pads in the middle of a bath matt flat on the floor. The wee pad is the target but a rubber backed bath matt catches what ever he may miss and they wash up very well. Maybe I do too much for my Tater. You would just have to meet him to understand why.

I have used the pet litter with raising pups in the winter in Colorado. I switched to using the cat type pellets that are made from recycled newspaper. If the dog is not eating the pellets, you can use the pine pellets make for woodstoves. They are a whole lot cheaper and smell good.