there are several that I have found where people write regarding problems they have had with their cats ingesting sodium bentonite. I think it is more of an issue about the amount ingested, considering the small size of a cats intestine. My kitties lick themselves all the time and I would think they could overdose with very little effort between what they kick up when scratching the litter and then with grooming. It would make sense to me that an overabundance of anything can have harmful side effects. After all, they mention the problems only where chronic use is concerned.