Thanks to
siderea for pointing me to
this post about problems with Purina pet food (dog and cat, at least). After seeing this I read the last several month's worth of
consumer-affiars complaints, and older ones about the specific foods relevant to me. (Warning: can be gross.) This goes well beyond "ew, yuck" to "get that stuff out of the house before it contaminates anything else". Fortunately I don't use their dry food (infestations), but I do -- or did, until now -- use Friskies canned food (toxins) sometimes.
I didn't find anything on Purina's site about this. Since this isn't in the news I don't know how I would hear about a response from them other than searching from time to time.