Potassium bromate is the additive the food industry lists as E924a. In our table it is high risk: it takes 30 points off the additive subscore, which is worth a third of a product's score (about 10 of the 100).
- The key finding, from IARC: Group 2B, possibly carcinogenic to humans, on sufficient evidence of renal tumours in experimental animals (IARC Monographs Vol. 73 (1999), potassium bromate)
- No child flag. The class, and the points it costs, are the same for a child of any age.
- Where you meet it. None of the 10,000 packaged foods scanned most on Open Food Facts list it. Nine in ten of those foods are sold in Europe (counted 26 Sep 2026).
- 4 citations from IARC, US state law, OEHHA and the FDA, each one below.
What Potassium bromate does to a score
A packaged food's additive subscore starts at 100 and loses points for each additive on the label; that subscore is a third of the final score. Potassium bromate takes 30 points off the additive subscore, which is worth a third of a product's score (about 10 of the 100). Scan the pack in Sito and the score you get is the one for your own child's age, with this additive named in the reasons. How we score has the whole method.
See what is in your own cupboard
Scan a packaged food and Sito names the additives in it, then scores the product out of 100 for your child's age.
What the sources found
Every classification in our table comes from the citations below, and nothing else. Each finding is our one-line summary of what the source concluded, with the source and reference beside it.
-
IARC
Monographs Vol. 73 (1999) — potassium bromate
Group 2B, possibly carcinogenic to humans, on sufficient evidence of renal tumours in experimental animals. -
US state law
California AB 418, the California Food Safety Act (signed 7 Oct 2023), Health & Safety Code
Prohibits the manufacture, sale or distribution of any food containing potassium bromate in California from 1 January 2027 (with Red 3, BVO and propylparaben). -
OEHHA
Proposition 65 list of chemicals (OEHHA, list current to 31 July 2026) — potassium bromate/bromate, listed as causing cancer 1 January 1990
Listed carcinogen under California Proposition 65. -
FDA
21 CFR part 137 (Cereal flours and related products) — bromated flour; FDA post-market chemical review table (2024)
Still federally permitted as an optional flour treatment in the US; FDA lists potassium bromate in 'review of information' status since March 2024.
Why this class
IARC Group 1 or 2A with a dietary exposure route; or EFSA has withdrawn or negated a safety conclusion; or EFSA’s own exposure assessment finds a child age group exceeding the ADI at mean intake; or the substance is banned or formally being phased out for food use by the EU, by the US FDA, or under a US state law.
Our confidence in this row's classification is high. Medium or low does not mean the evidence is weak; it means something about the row is still being pinned down, usually a regulatory status confirmed from one source rather than two.
Questions parents ask
Is Potassium bromate (E924a) safe for kids?
High risk. In Sito it takes 30 points off the additive subscore, which is worth a third of a product's score (about 10 of the 100). The finding we rely on: Group 2B, possibly carcinogenic to humans, on sufficient evidence of renal tumours in experimental animals (IARC Monographs Vol. 73 (1999), potassium bromate).
What is E924a?
E924a is the E number for Potassium bromate, an additive. Open Food Facts tags it en:e924a.
Next to it on the label
The E numbers either side of E924a in our table, then the closest additives of the same kind by number.
- L-cysteine (E920), no risk identified
- Chlorine dioxide (E926), no risk identified
- Azodicarbonamide and carbamide (E927), low risk, flagged for young children
- Azodicarbonamide (E927a), low risk, flagged for young children
- urea (E927b), no risk identified
- Calcium peroxide (E930), no risk identified