New hamster, perhaps?

[IRescue452]

Reggie-you've got that backwards, cedar has the worst effects. But if it doesn't cause problems with your hammie...

I have a mousery and I also have rats. Mice and rats contain a bacteria in their bodies that makes them more prone to respiratory infections than hamsters. This means they are more sensitive to bedding. I find kiln-dried pine to be the best option after soil. Even carefresh is bad because of all the tiny dust particles. The problem is finding a pine bedding that is actually rinsed and kiln-dried. I buy huge packages of America's choice at the hardware store that are meant for horse stalls. The stuff from pet stores seems to bring out the worst in my mice. Kaytee and the walmart brands (names evade me) are bad- they say kiln-dried but they still smell of hydrocarbons and give my mice red noses. Anyway, I talk to tons of mousery owners who raise show mice, and many agree that pine is a good bedding, you just have to watch your rodents and get a decent brand.

Here is a very good site to look at (though phenols are blamed instead of hydrocarbons)
http://members.tripod.com/~antigonemeans/phenols.html

This one's a little more sciency, but it backs up my belief that phenols aren't the problem (hydrocarbons, cedrene oils, and general bacteria associated with untreated beddings are the problem)
http://www.geocities.com/heavyhitter1.geo/Pine.html