This article refers to clumping clay litter...very different from the liquid Bentonite used in a colon cleanse. There are many different types of clay and some of them are not intended for internal use. Also, the concentration of clay used during a cleanse is very different than eating clumps of clay...this is why hydrated liquid Bentonite is used. Furthermore, cat litter manufacturers are not going to use 100% bentonite...too expensive, and they wouldn't be concerned about purity....there's no telling what is in cat litter!