Which version are you using? I looked at site- it says their products use "selected natural raw material: poplar, aspen, cellulose, corn cob"
I don't think any of those ingredients would be dangerous, unless they're EATING it- & I'm thinking perhaps the corn cob would be appealing? & could cause blockages in their GI tract?
As I said, I've no experience with ASFs, but this could explain it. What's on your package labeling???
I looked again under "premium scientific bedding" & they also use "Spruce" in some formulations. What did you buy? I think spruce might be iffy?