Butylated hydroxyanisole

• BPButylated Hydroxyanisole
• Ph. Eur.Butylhydroxyanisole
• USP–NFButylated Hydroxyanisole

BHA; tert-butyl-4-methoxyphenol; butylhydroxyanisolum; Nipanox BHA; Tenox BHA; E320

2-tert-Butyl-4-methoxyphenol and 3-tert-butyl-4-methoxyphenol (mixture) · [25013-16-5]

UNII 62RAC24292 · PubChem CID 8456

C11H16O2 · 180.25

Antioxidant, chelating agent

Typical concentrations: 0.005–0.02% topical · Dosage forms: Semi-solid, Solid, Liquid

An antioxidant used to delay rancidity in fats, oils and oil-containing formulations and to protect oxidation-sensitive drugs and vitamins. Typical levels are 0.005–0.02% in topical products and up to about 0.02% of the fat or oil content in oils and foods; it is also used in some injectable products at low concentrations. It is often used together with BHT, propyl gallate and a chelating acid such as citric acid, which act synergistically.

A white or almost white crystalline powder or a yellowish-white waxy solid with a faint, characteristic aromatic odour.

Melting point

about 47 °C (commercial material)

Boiling point

about 264 °C

Solubility

practically insoluble in water; freely soluble in ethanol, methanol and propylene glycol; soluble in fats, fixed oils and dilute alkali hydroxide solutions

Composition

mainly the 3-tert-butyl isomer, with a smaller proportion of the 2-tert-butyl isomer

Exposure to light causes discolouration and loss of activity. Store in a well-closed container, protected from light, in a cool, dry place.

Incompatible with oxidising agents. Traces of iron salts produce discolouration.

Prepared by tert-butylation of 4-methoxyphenol with isobutene (or tert-butanol) in the presence of an acid catalyst; the product is a mixture of the two positional isomers.

At the low levels used in medicines and foods BHA is generally regarded as safe, although very high doses produced forestomach tumours in rodents and IARC classifies it as possibly carcinogenic to humans (Group 2B); the relevance to humans, who lack a forestomach, is doubtful. EFSA has set an ADI of 1.0 mg/kg body weight and JECFA an ADI of 0–0.5 mg/kg. Occasional skin irritation and contact sensitisation have been reported.

Observe normal precautions for the quantity handled. BHA may irritate the eyes and skin; eye protection and gloves are recommended. Avoid heating to decomposition, which gives off irritant fumes.

GRAS listed. Accepted as a food additive in Europe (E320). Included in the FDA Inactive Ingredient Database (oral capsules and tablets, topical, rectal and vaginal preparations and some injections) and in medicines licensed in Europe.

Butylated hydroxytoluene; propyl gallate; tert-butylhydroquinone; tocopherol.

BHA is fat-soluble and works best in the oil phase; it is particularly effective in protecting animal fats and essential oils and in preventing loss of volatile flavours. It has some antimicrobial activity of its own but is not used as a preservative for that purpose.