Potassium bromate, for example, is also illegal in Canada, China, the European Union, Brazil, India, the United Kingdom, and elsewhere because it causes cancer. In the United States it has been legal to add to food since it was first patented for use in baking bread in 1914.
Troy Farah writing for The Guardian:
But despite petitions from several advocacy groups – some dating back decades – the US Food and Drug Administration (FDA) still considers these to be Gras or “generally recognized as safe” to eat, though plenty of experts disagree.
“The system for ensuring that ingredients added to food are safe is broken,” said Lisa Lefferts, senior scientist at the consumer advocacy group Center for Science in the Public Interest. Lefferts, who specializes in food additives, said that once a substance is in the food supply, the FDA rarely takes further action, even when there is evidence that it isn’t safe.
The Center for Science in the Public Interest petitioned the FDA to ban potassium bromate two decades ago due to cancer concerns, but the FDA’s response, according to a letter from the agency, was that it couldn’t examine the issue due to “limited availability of resources and other agency priorities.”