Is biodegradable cat litter safe to use in rat litter box?

I currently use bathing sand in my rats’ litter box but I’d like to change it to something I can just flush down the toilet (it would be much more convenient). I tried using tissues but they just take them out of the box to play with. So I thought about that biodegradable soya based or corn based cat litter but I don’t know if it is OK to use for rats (and I couldn’t find any information on it).