Azodicarbonamide (ADA)
Last reviewed October 18, 2026 · Evidence strength: Limited · How we grade evidence
In plain words: Azodicarbonamide is a flour "conditioner" that makes bread dough stretchier. It isn't allowed in European food, and baking turns part of it into a substance (semicarbazide) that caused tumors in animals at high doses. The asthma reports involve factory workers breathing the powder, not people eating bread. Many US breads skip it, so it's an easy one to avoid.
Also listed on labels as: Azodicarbonamide, ADA, ADCA
What is it, and why is it in food?
ADA bleaches flour and strengthens dough. US rules allow up to 45 parts per million in flour. It's in some breads, buns, sandwich rolls and prepared sandwiches. It's also used to make foam plastics, but lots of safe substances have industrial uses too, so that alone isn't the concern.
What does the science say?
| The popular claim | "Azodicarbonamide, a dough conditioner also used to make foam plastics, is banned in Europe and causes asthma and possibly cancer." (Widely spread in 2014; none of the five experts we reviewed made it.) |
| Our verdict on that claim | Partly supported |
| Evidence strength | Limited: worker case reports, animal data on a breakdown product and regulator action; human dietary risk unmeasured. |
| Kinds of studies | Worker case reports, animal studies, lab analyses, regulatory rules |
- Breakdown during baking: Semicarbazide doesn't form while mixing dough; it appears during baking, through a step called biurea.1 Levels are higher in baked products than in the flour.2
- Asthma: Four factory workers developed asthma after breathing ADA powder.3 A 2017 review said even that evidence is "less than persuasive."4 Eating bread isn't the same exposure.
What do regulators say?
- FDA: permitted up to 45 ppm in flour.5
- EU: not authorized as a food additive.
- FDA listed ADA in its 2026 post-market chemical review and launched a reassessment in May 2026.6
Who should be careful?
- No group has proven harm from eating it. It has no nutritional benefit, so skipping it is a no-cost precaution.
How common is it in US foods?
In our check of USDA's Branded Foods database, 795 of 438,129 US packaged foods with an ingredient list name azodicarbonamide (about 0.2%, or roughly 1 in 551).7 It shows up most often in: breads & buns (356); prepared subs & sandwiches (145); cakes, cupcakes, snack cakes (52); frozen appetizers & hors d'oeuvres (43); croissants, sweet rolls, muffins & other pastries (36). Breads, buns and prepared sandwiches account for most of them. These are label records companies sent to USDA, mostly in 2021 to 2023, so some products have changed since. Counts come from a text match of ingredient lists and are approximate.
Swaps and tips for families
- Compare bread and bun labels; most brands don't use ADA.
- Bakery bread rarely contains it.
Beyond the plate: related non-food exposures
ADA's main non-food use is as a blowing agent in foamed plastics and rubber, like yoga mats, shoe soles and gaskets. Workers breathing the powder is the documented asthma risk.
Frequently asked questions
Is azodicarbonamide banned?
It's not allowed in EU food. In the US it's permitted up to 45 ppm in flour.
Is azodicarbonamide the yoga mat chemical?
It's used in foam plastics like yoga mats, but that nickname is misleading. The real question is semicarbazide, which forms during baking.
Is azodicarbonamide safe to eat?
Human risk hasn't been measured and is likely small, but it offers no benefit to you, so it's an easy one to skip.
Related guides
Sources
Every source below was checked against PubMed, the publisher or the official page by our research team in October 2026.
- Semicarbazide formation in flour and bread. Journal of agricultural and food chemistry, 2008. PubMed 18303820 · doi:10.1021/jf073198g
- Assessment of the determination of azodicarbonamide and its decomposition product semicarbazide: investigation of variation in flour and flour products. Journal of agricultural and food chemistry, 2011. PubMed 21786817 · doi:10.1021/jf201819x
- Occupational asthma after exposure to azodicarbonamide: report of four cases. British journal of industrial medicine, 1989. PubMed 2920144 · doi:10.1136/oem.46.1.60
- Azodicarbonamide (ADCA): A reconsideration of classification as a respiratory sensitiser. Regulatory toxicology and pharmacology : RTP, 2017. PubMed 28734852 · doi:10.1016/j.yrtph.2017.07.018
- 21 CFR 172.806 Azodicarbonamide. Link
- FDA post-market chemical assessment: FY2026 work plan. Link
- FoodData Central, Branded Foods dataset (release 2026-04-30). U.S. Department of Agriculture, Agricultural Research Service, 2026. Link
This guide is for general education. It is not medical advice and does not replace advice from your doctor, pediatrician, allergist or registered dietitian. If you think you or your child reacted to a food, talk to a health professional. Research changes; we review these pages when new evidence or rules come out. Last reviewed October 18, 2026. Spotted an error? Email [email protected].