The link http://exoticpets.about.com/cs/guineapigs/a/woodshavings.htm has a good article titled "The Problem with Cedar and Pine Shavings as Pet Bedding and Litter" and references some of the studies done.

Traditionally pine shavings has been used as bedding material for chinchillas and other small animals however recent studies have indicated that the aromatic hydrocarbons, phenols and oils that are not as strong as cedar have also been implicated as potential health risks primarily with regards to respiratory problems and changes in the liver.

Oxbow Hay Products states regarding chinchillas "Cedar and pine shavings are not recommended, because they contain resins that can be irritating to your pet's skin, eyes, and mucous membranes." (http://www.oxbowhay.com/link.sp?page=Chinchillas)

Sun Seed states in their online Chinchilla Care Guide "recent studies indicate that the phenols in pine that cause their aroma, also can lead to health problems in animals that have direct exposure over an extended period of time. Aspen bedding is a much better and safer choice." (http://www.sunseed.com/artccat315FPCNL.html)

With the recent growth of chinchillas being kept as pets long term health and life longevity have become of greater concern.

We at Flower Town Chinchillas have switched from pine to aspen for our chinchillas cage bedding. We carry a supply of Top Grade Quality Aspen at pricing competitive with that of pine to help promote a healthier choice for your chinchillas.