Is Fresh Step crystal cat litter safe if eaten by a chihuahua?

I have a 5 pound chihuahua that eats everything he finds on the floor. We also have a cat and we used to use all natural litter, then we got an automatic box that can only use one type of litter: fresh step crystals, which claim that they are safe for cats, but I am worried of my chihuahua eating the little chunks. We keep the box in another closed off room from the dog, but the litter will track. Does anyone have medical history with dogs and can give advice what will happen if he eats a few crystal chunks? (these are not crystalline silica, but silica gel, which they claim are safer for pets, even if ingested...but how can this be safe if ingested?)