Potassium bromate, chemical formula KBrO3, is a chemical that is used in the United States and numerous other countries as a flour improver and dough conditioner, and which is classified as a carcinogen and banned in the EU, China, India, and many other countries.
When baked, potassium bromate is converted to potassium bromide, KBr, which is not carcinogenic. Due to concerns of potentially risks if additives were improperly measured or baked goods were incompletely baked, however, many governments have chosen to ban the additive completely.
The safe level determined by the US FDA was 20 parts per billion (or 0.02 μg/g). Testing (in 2021 and 2023) of bread by scientists in Cameroon and Bangladesh, where potassium bromate use is unregulated, found that bread samples routinely exceeded that level by 10 to 100 times, suggesting that dangerous levels of potassium bromate are still in use in some markets worldwide.
Currently, the United States FDA urges bakers not to use potassium bromate, but has not banned it entirely. The state of California has banned it, in a law that takes effect in 2027, and the state of New York is considering a ban.
Potassium bromate is banned in the European Union, China, India, Canada, Argentina, Brazil, Nigeria, South Korea, Australia, New Zealand, Peru, and Sri Lanka.