I bred rats for the pet and show trade for many years. I do not reccommend using newspaper.. the inks can cause problems for the rats/mice. I reccommned using carefresh. Pine is OK, and there have very few reports of problems associated with pine, however, do not use anything with clorophyl. Clorophyl is dangerous. Also do not use ceder. Ther are also many other types of bedding reccommended commercialy for rodents, some look like pellets... they work OK, but, they do not absorb urine well, and that leads to a problems of its own.