Probably because it essentially IS sawdust. LOL.
The 9th ingredient is Microcrystalline Cellulose and as the name implies, is basically cellulose and is derived from high quality wood pulp. It's 9 ingredients down so it probably doesn't make up a ton of the food, but yeah, it's in there.
And then Carboxymethyl Cellulose is one of the organic chemicals used for adhesives, dispersants, emulsifiers, etc. Sodium Carboxymethyl cellulose is often used for drilling fluids grade, for paints grade, for paper grade, for ceramics grade, for construction grade, for textile printing grade, etc and is often sold from China. Not to mention it's preserved with BHA and BHT.
And basically all those other ingredients in the food that we probably don't know what they are... any time an ingredient list is made up of a bunch of things that we have no clue what they are, or what's in them, or where they come from... they are probably bad for us.
lol. Of course we all still usually eat them anyways, in people foods; I am trying to get better at ingredient reading, but at least we can be conscious of what we're feeding our pets since they do not have a choice what they eat.
Jackson ate a half of a Frosty Paws once with no ill effects, but I probably wouldn't offer it to him again, he did not seem to like it much anyways.