I subscribe to petfoodindustry.com and found this blog post long, but an interesting read regarding ingredients found in pet food. Article contents range from Bisphenol A all the way to Pea protein. If you have some time it's worth perusing.
http://www.petfoodindustry.com/Defau...18&pageid=1677
http://www.petfoodindustry.com/Defau...18&pageid=1677