The fertilizer plant where I used to work also sold feed. Used to import semi-loads of cottonseed for use as dairy feed, the cows just loved the stuff.

I think the fact that cottonseed can now be fed to other types of livestock is far more important than it being used by humans. But unless there is something that you can specifically see or a very simple test the chance of getting the wrong kind is high.

Here in Michigan flame retardant got accidentally mixed in animal feed causing the PBB crisis. As a result most citizens of the state have measurable levels in their blood. There was even a TV movie with Art Carney and Ron Howard. I was friends with the farmer who wrote the book upon which the movie was based.

http://www.michiganradio.org/post/michigans-toxic-1973-pbb-f...