Consumer advocates at the Environmental Working Group are warning that a chemical used to make yoga mats and flip-flops can now be found in more than 500 food items. The chemical, azodicarbonamide, is often used in bread, croutons, pre-made sandwiches and snacks made by many major brands, including Pillsbury, Nature’s Own, Sara Lee, Kroger and Little Debbie. The restaurant chain Subway recently announced it was phasing out the use of the chemical after an online campaign. The chemical is not approved for food use in Australia and Europe.