Bromate flour treatment agents
A flour treatment agent that IARC classes as possibly carcinogenic to humans. Not permitted in the EU; still allowed in some countries.
- Category
- Flour treatment agents
- Vegan
- Yes
- Vegetarian
- Yes
What it is
E924 is the legacy umbrella code for the bromate flour treatments, since split into E924a (potassium bromate) and E924b (calcium bromate).
How it is used in food
It oxidises flour proteins so dough rises higher and holds a finer crumb — the reason it survived so long in industrial baking.
Commonly found in- Commercial bread (in permitted countries)
Health and safety
Caused kidney and thyroid tumours in animal studies, which is why IARC places it in Group 2B, possibly carcinogenic to humans. Most of it breaks down during baking, but residues can remain.
Not authorised in the EU. Where you meet this number it is a legacy listing; the specific substances are E924a and E924b.
Regulatory status
| Region | Status | Notes |
|---|---|---|
| Australia & New Zealand FSANZ |
Banned | Banned due to carcinogenic concerns. |
| European Union EFSA / European Commission |
Not approved | Not on the EU authorised list of food additives (Annex II). |
| United States FDA (Food and Drug Administration) |
Permitted | Permitted in the US as a dough conditioner, despite bans in other regions. |
Identification on labels
- E-number
- E924
Worth knowing
It works during baking and is largely consumed by the reaction, which is why the argument over it turns on how much survives in an under-baked loaf.
Conclusion
A carcinogenic dough conditioner banned in most of the world.
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Open the appEntry last reviewed 2026-08-05.
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