I'm sorry to say but yes it is, check out the site that I just put up. I've had rats and mice as pets since I was 8. They are most def. toxic, They cause bad respitory problems.

"The acids given off by pine and cedar shavings are very damaging to the respiratory tract. These acids can actually destroy cells that line the lungs and trachea (2). This has significant implications for rats since the most common diseases in pet rats are respiratory infections. Many owners of pet rats have reported the improvement of respiratory problems when they have switched their pets to a bedding other than pine or cedar shavings. " This is stated on that site and by many many rat breeders and mice breeders.