I've never used the stuff but have been told by people who have (for hamsters) that it moulds very quickly and is a hotspot for growing the deadly aspergillus fungus.

I have also heard that if ingested it can swell causing an internal blockage.

Personally for my hamsters I use carefresh and for the gerbils either shredded cheap toilet paper or paper horse bedding which is made out of toilet paper like stuff.

Are we talking about rats I guess? If so my friends use yesterdays news paper cat litter.