In this particular context, take the subtitle as sarcasm. This post is another pop-sci excerpt, but it’s not the science I’m highlighting, rather the bad use of it. Some food blogger decides to make a name for themselves and uses an emotional and contextual response to sway opinion about an ingredient in bread. In short order the popular food franchise, Subway takes steps to remove it from their bread baking process altogether. Is it unsafe? Nope. Do you want to eat something that’s also found in yoga mats? Exactly..
In plastic, azodicarbonamide is a blowing agent; in bread it is an oxidizing agent that helps polymerize the wheat proteins into a better gluten network. We need to look at the chemistry to determine if the uses are appropriate. Azodicarbonamide itself is safe at the levels used in bread (45 ppm). There are a few toxicology reports, but these are mainly associated with respiratory hazards as a bulk chemical. Part of the reason it is so safe is it reacts rapidly with the bread to form biurea, which is even less toxic. However, there are more substantive concerns around some further breakdown products, semicarbide and in particular, urethane (ethyl carbamate). In a controlled baking study the FDA tested showed urethane is higher in bread made with azodicarbonamide (2.4 vs 5.4 ppm).
You have to eat huge amounts of urethane to get any toxic effects, but at lower levels it is a known animal carcinogen and reasonably expected to be a human carcinogen. Alcoholic drinks often contain high levels of urethane; cherry brandy is particularly bad (~2000 ppm) but we (hopefully) don’t drink too much cherry brandy. Other fermented foods contain urethane at lower levels and bread is of special concern as we eat so much of it. And guess what? Urethane is found in bread made without the additive.