Potassium bromate
KBrO₃ · E924 · "bromated flour" · "dough conditioner"
A chemical oxidizer added to wheat flour to strengthen dough, produce taller loaves, and speed up commercial bread production. Banned in the European Union, United Kingdom, Canada, Brazil, China, India, and most of the rest of the world — but still legal in the United States.
Why we flag it
The International Agency for Research on Cancer classifies potassium bromate as Group 2B — "possibly carcinogenic to humans" — based on multiple animal studies showing kidney, thyroid, and abdominal tumors at dietary levels. The compound is supposed to fully convert to harmless potassium bromide during baking, but residual levels frequently exceed permitted thresholds when bread is under-baked, under-proofed, or made with too much bromate.
The U.K. banned it in 1990. California requires a warning label on any food containing it under Prop 65. The FDA has acknowledged the carcinogenic data for decades and "urges" bakers to find substitutes but has never formally restricted its use — making the U.S. one of very few developed nations where it remains common in commercial bread.
Where you'll find it
Almost exclusively in commercial baked goods made with bromated flour:
- Bagels, pizza dough, and pretzels from large chains
- Cheap loaf breads and sandwich buns at discount grocers
- Refrigerated and frozen biscuit, pizza, and pastry dough
- Some commercial cake mixes and donuts
- Restaurant breadsticks, rolls, and sandwich loaves served in chains
The dead giveaway on a label: "bromated flour," "potassium bromate," or "enriched bromated flour" listed in the first few ingredients.
What to look for instead
Plenty of bread is made without it — you just have to read flour names carefully:
- "Unbromated flour" — the explicit signal on many premium and natural-brand breads
- Organic flours and breads — USDA Organic prohibits potassium bromate entirely
- Whole-grain, sprouted, or sourdough loaves — typically made without bromate
- Local bakery bread — most small bakers haven't used bromate in years
- Ascorbic acid (vitamin C) doughs — the most common modern substitute, much cleaner safety profile
If your bread doesn't list potassium bromate and the rest of the ingredient list is short and recognizable, you're in good shape.