Bromated flour contains potassium bromate, an oxidizing agent widely used in commercial baking to strengthen dough and promote rising. Some brands of flour sold in supermarkets for home use contain potassium bromate. Studies dating back to 1982 found that the chemical causes several types of cancer in lab rats. For that reason, potassium bromate is considered “possibly carcinogenic to humans” by the International Agency for Research on Cancer. Bromated flour is banned by a number of governments including the European Union, Canada, Brazil, Peru and China.
In the U.S., the FDA has encouraged bakers to voluntarily stop using bromated flour, but many have not. The agency continues to permit the use of the flour as long as potassium bromate doesn’t exceed .0075 parts for each 100 parts of the weight of the flour, or 750 parts per million. The only other regulation concerning the use of bromated flour is a California law that requires a store warning on any bakery goods made with it if the products contain more than a specified level of the chemical. As a result, most California bakers have switched to bromate-free flours.
Potassium bromate is supposed to cook out of bread as the dough bakes, thus removing any potential health threat. Some of it may not, however. When you buy commercial bread, baked goods or flour, look on the ingredient lists for “potassium bromate” or “bromated flour.”