AZO (some refer to it as ADA) is banned in much of the world. In the European Union, food cannot even be packaged in plastics containing AZO, let alone have the chemical as an ingredient.
A number of bread brands sold at Costco feature the additive. Among the products that are baked on-site, Costco's butter croissants and carrot walnut muffins are two of the products that have azodicarbonamide listed in the ingredients.
Yesterday, the Environmental Working Group released a list of nearly 500 food products sold throughout the United States that include azodicarbonamide. Costco baked goods were not among those listed.
Azodicarbonamide has been in the news a great deal lately after the blogger known as "Food Babe" (Vani Hari) started a petition to have the chemical removed from the breads at Subway. After more than 70,000 people signed the petition, Subway announced that they would discontinue using the "dough conditioner."
After speaking to several folks at Costco's corporate offices in Issaquah, Washington, a request has been sent to their media relations people to comment on the use of azodicarbonamide in products produced in their bakeries. Their response will be published when, and if, they make one.