You say "it's banned in Europe and Oz as a food additive" as if that was material or interesting. GMOs are banned in Europe too, but no one takes that as a serious indictment of GMOs. It is, rather, a demonstration of the anti-scientific stance of European law-makers.
If you have some data that increases the posterior plausibility of the proposition "Azodicarbonamide is toxic at the levels found in Subway bread", give it to us! Note that that statement is quite different from "azodicarbonamide is toxic at some level", because that statement is true of virtually everything and is therefore completely irrelevant to the question about it's use in Subway's bread.
I just mentioned the ban as an indication that there may be some drawbacks to the stuff. I see in the wikipedia mention that the UK has 'determined that containers of it should be labeled with "May cause sensitisation by inhalation."' Sounds like healthy and tasty to me.
If you have some data that increases the posterior plausibility of the proposition "Azodicarbonamide is toxic at the levels found in Subway bread", give it to us! Note that that statement is quite different from "azodicarbonamide is toxic at some level", because that statement is true of virtually everything and is therefore completely irrelevant to the question about it's use in Subway's bread.