If you want 100% assurance, you could always phone or email the manufacturer.
One of the problems with cats is there are so many normally harmless things that their liver enzmes are unable to process like other species so they get a buld up of toxins. I'm sure if it isn't stated on ingredients, it's fine but you may want 100% assurance. You could tell them their product is being recommended as cat litter but you want to check that theirs is listed as safe on cat forums.