# What are BHA and BHT? Understanding E320 and E321 on labels

> BHA (E320) and BHT (E321) are synthetic antioxidants that delay fats going rancid. The IARC classification and EFSA's intake limits only make sense when read together.

Published: 31 October 2026 — Antioxidants, E numbers, BHA, BHT

If you have seen "antioxidant: BHA" or "E321" on the label of a breakfast cereal, crisps, chewing gum or a packaged snack that contains fat, you have met an additive that delays fats from reacting with oxygen and turning rancid. BHA (butylated hydroxyanisole, E320) and BHT (butylated hydroxytoluene, E321) are synthetic antioxidants that have been used for this job for decades. Headlines about them tend to say "possible carcinogen." To understand what that does and does not mean, you need to read two institutions' assessments together.

## What are they for?

In foods that contain fat, fatty acids oxidise on contact with air, which spoils taste and smell: the product goes rancid. BHA and BHT slow that chain reaction and so extend shelf life. They can also be found in some packaging materials. Use limits are set per food category; in the United States the FDA regulations list both as permitted additives in specified foods ([BHA: 21 CFR 172.110](https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-B/section-172.110), [BHT: 21 CFR 172.115](https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-B/section-172.115)). Their use is legal and limited, not banned outright.

## What IARC says: Group 2B

The International Agency for Research on Cancer (IARC) addressed BHA in [Volume 40 (1986)](https://www.inchem.org/documents/iarc/vol40/butylatedhydroxyanisole.html). It found sufficient evidence of carcinogenicity in experimental animals (forestomach tumours in rats and hamsters) and no human data adequate to evaluate. In Supplement 7 (1987) BHA was placed in Group 2B, "possibly carcinogenic to humans."

How to read Group 2B matters. IARC classifications describe whether a substance can cause cancer (the hazard), not how much risk it poses at the amounts found in ordinary food. And the animal tumours appeared in an organ humans do not have in the same form: the forestomach of rodents.

## What EFSA says

The European Food Safety Authority re-evaluated both substances:

- **BHA (E320)**: in its [2011 opinion](https://efsa.europa.eu/de/efsajournal/pub/2392), the panel found no genotoxicity concern and raised the ADI (acceptable daily intake) from 0.5 to 1.0 mg/kg body weight per day. Its reasoning: forestomach hyperplasia in rodents may no longer be relevant for human risk assessment, and the new limit rests on a no-effect level (NOAEL, 100 mg/kg/day) based on growth retardation and behavioural effects in rat pups. At current use levels, refined intake estimates are generally below the new ADI.
- **BHT (E321)**: in its [2012 opinion](https://efsa.europa.eu/en/efsajournal/pub/2588), the panel found no genotoxicity concern, considered any carcinogenic effect to be threshold-based, and raised the ADI from the previous 0-0.05 to 0.25 mg/kg body weight per day. Adult exposure is unlikely to exceed the ADI; for children, mean exposure does not, but the 95th percentile does in Finland and the Netherlands.

So the two bodies look at the same topic from different angles. IARC says "this substance can produce tumours in animals." EFSA says "at current use levels, estimated intake is generally below the safe limit we set." They do not contradict each other; they answer different questions.

## Reading the label

1. BHA and BHT appear in the ingredients list under "antioxidant" or by name. E320 and E321 are the same substances.
2. The products that contain them are typically fatty, long-shelf-life foods: breakfast cereals, crisps, chewing gum, crackers and packaged snacks.
3. Some manufacturers use other antioxidants instead, such as E306 (tocopherols, i.e. vitamin E) or rosemary extract (E392). These also show up on labels.
4. Total exposure is what counts: it depends less on one product than on how often products containing the substance appear in your daily diet.
5. If you suspect a sensitivity, ask your doctor.

## In LogicFood's research records

In LogicFood's additive research records, BHA and BHT carry the highest risk level (High). The sources behind them are the IARC evaluation and FDA/eCFR regulations above, plus EFSA's BHT opinion. The marker is a prioritisation signal derived from IARC's Group 2B classification. It is not a ban and not a verdict about anyone's health.

## In short

Calling BHA and BHT simply "carcinogenic" or simply "safe" would each leave something out. The finding in animal studies, the ADIs set by regulators and real intake levels should be read together. With the label in hand, you can recognise these substances and make your own choice.

Sources: [IARC Monographs vol. 40, BHA](https://www.inchem.org/documents/iarc/vol40/butylatedhydroxyanisole.html) · [EFSA, re-evaluation of BHA (E 320), 2011](https://efsa.europa.eu/de/efsajournal/pub/2392) · [EFSA, re-evaluation of BHT (E 321), 2012](https://efsa.europa.eu/en/efsajournal/pub/2588) · [eCFR 21 CFR 172.110](https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-B/section-172.110) · [eCFR 21 CFR 172.115](https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-172/subpart-B/section-172.115)

https://logicfood.app/en/blog/bha-bht-antioxidants/