Much of the flour sold in the United States has been treated with potassium bromate, which causes the flour to bulk up, strengthens the dough, and makes bread rise more rapidly. This decreases the time needed for baking (thereby reducing costs) and also allows the use of low quality flour that might otherwise be unsuitable for baking. There's only one problem with this: Potassium bromate causes cancer. Potassium bromate is so widely accepted as a carcinogen that it has been banned in the European Union, Canada and even in China. U.S. law only allows the chemical to be used as an ingredient in food because it was first approved by the FDA back in 1958, before modern anti-cancer legislation went into effect. The fact that the ingredient has actually received FDA approval makes it much more difficult for it to be subsequently banned.
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