BHA
A synthetic antioxidant added to fats, oils and snack foods to stop them going rancid. Classified as a possible human carcinogen.
Classed as a possible human carcinogen based on animal studies showing forestomach tumours at high doses. The US National Toxicology Program goes further, listing it as reasonably anticipated to cause cancer in humans.
What is it?
Butylated hydroxyanisole (BHA) is a synthetic, fat-soluble phenolic compound used as an antioxidant in food. It is a mixture of two isomers: 2-tert-butyl-4-hydroxyanisole (the minor component) and 3-tert-butyl-4-hydroxyanisole (the major active isomer).
What does it do?
BHA works by donating a hydrogen atom to free radicals produced when fats oxidise, interrupting the chain reaction that causes rancidity. Because it is fat-soluble, it stays within fatty food matrices and remains active even at cooking temperatures. It is often used alongside BHT (E321) and other antioxidants in combination.
Where you will see it
Vegetable oils, lard, butter blends, crisps, biscuits, crackers, breakfast cereals, nut products, chewing gum base, dried potato snacks, instant noodles, flavourings, and food packaging materials that carry it into food. On a UK label it appears as 'E320' or 'butylated hydroxyanisole'.
What the science says
Animal studies and IARC Group 2B classification
Repeated feeding of high doses of BHA to rats and hamsters produced benign and malignant tumours in the forestomach, an organ humans do not have. IARC reviewed this evidence in 1986 and classified BHA as Group 2B, meaning 'possibly carcinogenic to humans'. IARC has since noted that the forestomach tumour mechanism may not apply to humans, but the Group 2B classification remains in place. Human epidemiological data are inadequate to draw a firm conclusion.
BHA induced benign and malignant forestomach tumours in rats and hamsters fed high dietary doses.
IARC classified BHA as Group 2B (possibly carcinogenic to humans) based on sufficient evidence in animals and inadequate evidence in humans.
BHA is listed as 'reasonably anticipated to be a human carcinogen' in the US National Toxicology Program 15th Report on Carcinogens.
EFSA re-evaluation and the ADI
The European Food Safety Authority established an ADI of 1.0 mg per kg of body weight per day based on liver and kidney findings in animal studies. A 2012 EFSA exposure assessment concluded that typical dietary intake remained below the ADI for most population groups, though infants and toddlers with diets high in processed foods could come closer to it. EFSA has noted a data gap on genotoxicity that had not been fully resolved at the time of that assessment.
EFSA set an ADI of 1.0 mg/kg body weight/day for BHA based on repeated-dose animal toxicity data.
Estimated dietary exposure to BHA was below the ADI for the general population but remained elevated in young children consuming high proportions of processed foods.
Skin and hormonal effects
Contact allergy and skin irritation have been reported in workers exposed to concentrated BHA. Some laboratory studies suggest BHA may interfere with androgen signalling at high concentrations, though the doses used in those experiments far exceed typical food exposure.
BHA has been identified as a contact allergen causing occupational dermatitis in food-processing workers.
In cell and animal studies at high concentrations, BHA showed anti-androgenic activity, disrupting androgen receptor signalling.
Where it stands with the regulators
Who should be careful
People with a known sensitivity to phenolic antioxidants or a history of contact dermatitis to BHA should check ingredient labels for 'E320' or 'butylated hydroxyanisole'. Parents seeking to minimise synthetic antioxidant exposure for young children, where processed-food intake is already high, may wish to note its presence. Anyone choosing to avoid IARC Group 2B classified substances should look for it in crisps, nut products, biscuits, cereals, instant noodles and processed meat products.
The honest read
BHA sits in an unusual position: approved by UK and EU regulators with an ADI, yet classified as a possible human carcinogen by IARC and listed as reasonably anticipated to be a human carcinogen by the US NTP. Regulators have argued that the rodent forestomach mechanism does not translate to humans, and that typical dietary exposure falls well below the ADI. Critics note that the genotoxicity question was not fully resolved at the time of the last EFSA re-evaluation, and that the NTP classification is based on the same animal data regulators are discounting. The honest picture is: the human cancer evidence is inadequate (not reassuring, just absent), the animal evidence is real, and the regulatory debate over mechanism plausibility has not been fully settled. The science is not closed.
Related additives
Common questions
Is E320 banned in the UK?
No. E320 (BHA) remains a permitted food additive in the UK under the assimilated EU Regulation 1333/2008. It is approved for use in specific food categories at defined maximum levels.
Is BHA classed as a carcinogen?
IARC classifies BHA as Group 2B, meaning 'possibly carcinogenic to humans', based on animal studies showing forestomach tumours. The US National Toxicology Program lists it as 'reasonably anticipated to be a human carcinogen'. European regulators have accepted that the specific tumour mechanism seen in rodents may not apply to humans, but the classification has not been revoked.
What foods contain E320?
E320 is found in crisps, nut products, biscuits, crackers, breakfast cereals, instant noodles, chewing gum, dried potato snacks, food flavourings, and some fat-containing products. It also enters food via the carry-over principle from permitted fats used in manufacture. Look for 'E320' or 'butylated hydroxyanisole' in the ingredients list.
Is E320 vegan?
BHA itself is synthetically produced and contains no animal-derived ingredients, so it is generally considered vegan. However, it is often used in animal fats such as lard and fish oil, so the vegan status of a specific product depends on the other ingredients, not BHA alone.
Sources
- IARC Monographs Volume 40: Butylated Hydroxyanisole (BHA) Summary and Evaluation
- US National Toxicology Program, 15th Report on Carcinogens: Butylated Hydroxyanisole
- EFSA Panel on Food Additives and Nutrient Sources: Statement on exposure to BHA (E320)
- UK Food Standards Agency: Approved additives and E numbers
- Butylated Hydroxyanisole: Carcinogenic food additive or harmless antioxidant? (ScienceDirect)
- EU Regulation (EC) No 1333/2008 on food additives (consolidated text)
Aaron Keen is the founder of NutraSafe. He researches and writes every additive entry himself, from the primary sources. About the research →
This is a guide, not medical advice. If an additive affects you, speak to your GP or a dietitian.
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