Azodicarbonamide, or ADA. This foaming agent has been making headlines for the past couple of weeks, due largely to the campaign of self-titled "Food Babe" Vani Hari to get Subway and other processed food manufacturers to remove it from their products. Although Ms. Hari did manage to extract a promise from Subway that it would phase out the chemical, it is likely to remain in the food supply for quite some time to come.
First, although neither the European Union (EU) nor Australia permit the use of ADA in food, the US Food and Drug Administration (FDA) permits its use in quantities up to 45 parts per million (ppm). Also used to make yoga mats and cell phone holders fluffy, ADA is used as a "dough conditioner" in the US. Although being "generally recognized as safe" (GRAS) or approved by the FDA seems as if it must be the result of a rigorous scientific investigation, it is in reality the result of approval by a small group of people or merely of longevity: food additives in wide use before 1958 are automatically considered to be GRAS. A long list of synthetic chemicals approved by the FDA for use in food is provided on the federal government's website here; the list includes polyethylene glycol, which often contains toxic impurities; polysorbate 80, which can be harmful to people with Crohn's disease; and white mineral oil, a refined petroleum product that is also not permitted in food in the EU.
The FDA permits food additives, generally speaking, not because they are beneficial to consumers, but because they make food preparation easier and / or cheaper for processed food manufacturers. There are plenty of alternatives to the ADA-containing breads on the market, as Ms. Hari explains in detail on her website. Dough conditioners do not improve the finished product; they simply reduce the time and effort involved in making the bread. The FDA admits that ADA, when used in food products, breaks down into semicarbazide (SEM); the FDA also admits that SEM causes cancer in female mice. However, there is no mention on the FDA's website of the DNA damage known to be caused by ADA and SEM, which was elucidated by Japanese researchers more than a decade ago.
Consumers wishing to avoid industrial chemicals in their food would do well to read all food labels, as food additives usually must be declared. (Some ingredients are controversial because the FDA has given its permission for manufacturers to declare them non-specifically as "other natural flavors." One such ingredient is castoreum, made from the crushed anal glands of a beaver and often used in processed foods that taste like vanilla or strawberry.) Consumers wishing to avoid ADA in particular can peruse the list of products compiled by the Environmental Working Group (EWG). This list includes such popular items as Arnold Bakery Light whole-wheat bread, Entenmann's raspberry Danish, Fleischmann's Simply Homemade baking mix, Freihofer's white bread, Hormel Country Crock homestyle stuffing, IHOP French toast breakfast sandwiches, Little Debbie cinnamon rolls, and Marie Callender's flaky croissants.