I checked out the DFA's references on menadione toxicity, and most of them involved large amounts of menadione (about 1 mM solution, which is quite a lot from a biological standpoint) that would never be purposefully fed to a dog. I think they were concerned about human exposure in labs that work with large quantities of menadione as a chemical reagent? One of the more interesting studies involved the injection of a human subject with menadione to counteract rat poisoning. He developed eczema at the injection site. Again, not likely to happen with dog food.
I found the following from the Handbook of Preservatives, by Michael and Irene Ash (2004): |