Potassium bromate

Potassium bromate is an oxidizing additive sometimes used to “condition” flour for commercial bread products, including some buns and rolls used in fast food. It can improve dough strength and oven rise. Baking is intended to convert bromate to bromide, but small residual amounts can remain if baking conditions aren’t well controlled. Because it caused tumors in animals and is classified as a possible human carcinogen, some places prohibit it, and California will ban it in foods starting in 2027. In the U.S., it can still be used within specified limits, so ingredient labels are the best way to spot it.

Aliases / Common Names: potassium bromate, KBrO3, bromic acid (potassium salt), bromated flour, flour improver, INS 924a Regulatory Status & Exposure: FDA’s standards of identity for bread/rolls/buns permit potassium bromate (including via “bromated flour”) up to 0.0075 part per 100 parts flour by weight (~75 ppm). FDA’s Food Substances database describes it as a flour treating agent/dough conditioner. WHO/FAO JECFA determined that use as a flour treatment agent is not acceptable because residues can remain in finished bread, and it does not allocate an ADI for that use. Canada does not list potassium bromate on its permitted flour treatment agent list (meaning it is not permitted for that function). California’s AB 418 delays implementation until 2027, after which foods containing potassium bromate are not allowed for sale in California. Technical Evidence: Potassium bromate is an inorganic bromate salt and a strong oxidizer. IARC reports no human cancer studies suitable for evaluation, but finds sufficient evidence of carcinogenicity in experimental animals (notably renal tubular tumors) and concludes an overall Group 2B classification. Mechanistic findings include lipid peroxidation, oxidative DNA damage, and genotoxicity in multiple test systems, supporting an oxidative-injury pathway that is particularly relevant to kidney tissue. Fast-Food Context: In U.S. fast-food supply chains, the most relevant exposure route is baked wheat items—burger buns, sandwich rolls, and similar bread components—where dough strength and volume help standardized, high-throughput production. If a supplier uses bromated flour, “bromated flour” or “potassium bromate” may appear in ingredient statements when labeling is available. Sensitive Populations / Notes: California’s Prop 65 lists potassium bromate for cancer and sets a 1 µg/day NSRL as a risk-based warning benchmark. For people who eat a lot of bread-based fast food (or those with kidney disease who want to be extra cautious), choosing non-bromated breads when possible is a practical exposure-reduction step.

We assign the high tier using published research, regulatory guidance, and PRūF’s additive taxonomy. Restaurant usage is derived from public ingredient disclosures and mapped to menu items where this additive appears.