As a mouse owner, I look down upon carefresh because of the dust. Dust won't harm a gerbil. No worries about them getting respiratory infections really, it doesn't happen often. But, I also don't like using fiberous beddings with heavy chewers like gerbils.

Pine, when kiln-dried properly, is great. Cedar is not. Both have hydrocarbons that can harm the rodents. Kiln drying gets rid of the hydrocarbons. Cedar has an extra toxin though, which is not removed through kiln-drying, called cedrene oil. This oil is toxic enough to cause liver damage and damage to other internal organs just through breathing it in.

Kiln-drying is touchy though. You have to find a company that does it right. Improper drying can lead to harmful molds. Don't use Kaytee or walmart brands. I prefer to use kiln-dried pine shavings from the farm supply store. The kind of stuff they use for horse stalls.

If you don't want any risk at all, use aspen bedding.

Don't listen to anything people say about phenols. If they'd done their research, they'd know that phenols are the beneficial part of pine and cedar.