Butylated hydroxyanisole (BHA) has been used for decades in various industries, including personal care products as an antioxidant and stabilizer to extend the shelf life of products. Personal care products such as lotions, lip balms, and hair products often contain synthetic antioxidants like BHA to prevent the oxidation of fats and oils.
Among its multiple applications, BHA is particularly useful in protecting the flavors and color of essential oils and is considered the most effective of all food-approved antioxidants for this application.
What is Butylated Hydroxyanisole (BHA)?
BHA is a monohydric phenolic antioxidant. Chemically, BHA is a mixture of two isomers, 3-tertiary-butyl-4-hydroxyanisole (90%) and 2-tertiary-butyl-4-hydroxyanisole (10%). Butylated hydroxyanisole is an antioxidant that imparts stability to fats and oils and should be added before oxidation starts. The conjugated aromatic ring of BHA can stabilize free radicals, sequestering them. By acting as free radical scavengers, further free radical reactions are prevented. The reaction of p-methoxyphenol with isobutene synthesizes it.
Butylated hydroxyanisole (BHA) chemical structure. Source: Wikipedia
Applications in Personal Care
Function
Applications
Antioxidant
Most fats, oils, and heavy fat-containing cosmetics are naturally susceptible to rapid rancidification and other oxidative reactions that produce compounds with objectionable taste and odor, making the product unpalatable. Lipid oxidation is autocatalytic and proceeds as a complex of chain reactions, the nature and speed of which vary with the substrate, temperature, light, availability of oxygen, and presence or absence of oxidation catalysts. BHA acts as a chain break, particularly effective in controlling the oxidation of short-chain fatty acids in the auto-oxidation processes under the usual conditions of processing, storage, and use of fat-containing personal care products. They are applied in the prevention of chain reactions by the stabilization of free radicals.
Stabilizer
BHA is used in certain products to stabilize and protect the raw materials themselves and less as an ingredient in and of itself. It can resist high temperatures (unlike some natural antioxidants), and therefore, is instrumental in raw material manufacturing processes. It is also added with precious active ingredients like Retinol, which is extremely heat sensitive,and helps stabilize the active ingredients.
Product Examples
BHA is used in various cosmetic products, including specific formulas containing fats or aqueous emulsions containing certain active ingredients or plant extracts. Here are some examples of products containing BHA:
Type
Examples
Hair Care
Hair masks contain many refatting agents, emollient systems, and conditioners to prevent oxidation.
Body & Face Care
Lotions, Creams, Body Butter
Cosmetics
Foundations, Eyeliners, Lipsticks. Suitable especially for anhydrous systems such as stick preparations and balms.
Sun Care
Sunscreens, Suntans, Aftersuns
Perfumes
Antioxidant Use at 0.1% in Citrus Oils and Aliphatic Aldehydes
Properties of Butylated Hydroxyanisole (BHA)
Appearance at 25 °C
White to pale yellow crystalline flakes or crystals or pastilles with a waxy appearance.
pH (10% Aqueous solution in water @25°C)
5-6.5
Molar Mass
180.246 g/mol
Density
0.9976
Refractive Index
1.4910
Solubility
Practically insoluble in water; soluble in methanol; freely soluble in ≥50% aqueous ethanol, propylene glycol, chloroform, ether, hexane, cottonseed oil, peanut oil, soybean oil, glyceryl monooleate, and lard, and in solutions of alkali hydroxides.
Odour
Characteristic Aromatic
Boiling Point
264-270°C
Melting Point
58-60 °C
Storage Conditions
Exposure to light causes discoloration and loss of activity. Combustible. BHA degrades with extended exposure to sunlight. Butylated hydroxyanisole should be stored in a well-closed container, protected from light, in a cool, dry place.
In direct addition, the fat or oil is heated to 60–70°C, and the BHA is added slowly under vigorous agitation. It may protect the fat-soluble vitamins A, D, and E. It is used singly or in combination with other antioxidants.
Safety & Regulatory Considerations
FDA Information
The FDA has listed BHA as “generally recognized as safe” (GRAS) for use in food.
EU Information
Accepted as a food additive in Europe. Included in the FDA Inactive Ingredients Database (IM and IV injections, nasal sprays, oral capsules, tablets, and sublingual, rectal, topical, and vaginal preparations).
Other Regulatory Information
Included in nonparenteral medicines licensed in the UK. Included in the Canadian List of Acceptable Non-Medicinal Ingredients.
Safety & Toxicity of Butylated Hydroxyanisole (BHA)
The European Commission on Endocrine Disruption has determined that there is strong evidence that BHA is a human endocrine disruptor.
Organ-system toxicity
Environment Canada’s Domestic Substance List has classified BHA as a high human health priority. A study carried out in normal mammalian kidney cells found that exposure to BHA caused specific damage at the cellular level and was found to exert a significant cytotoxic effect even at low doses.
Developmental and reproductive toxicity
Studies carried out in rats found that exposure to high doses of BHA resulted in weak dysfunction and underdevelopment of the reproductive systems of both male and female rats. Changes in testosterone levels, sex weight organs, and sexual maturation were also observed.
Cancer
Butylated hydroxyanisole (BHA) is reasonably suspected to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.
Identification Numbers
Chemical Name
Butylated hydroxyanisole
CAS Number
25013-16-5
EC Number
246-563-8
Acceptable Limits or Maximum Usage
The maximum usage level of BHA is as follows.
Category
Usage Level
USDA
Total content of antioxidants shall not exceed 0.01% w/w (100 ppm) of any one antioxidant or 0.02% w/w combined total of any antioxidant combination in animal fats.
Japanese regulations
1 g/kg in animal fats.
European Union’s Scientific Committee on Consumer Safety (SCCS)
BHA is safe for use in cosmetics up to a maximum concentration of 0.5%.
Fun Facts About Butylated Hydroxyanisole (BHA)
BHA was first synthesized in the late 1940s as a food preservative, and later it was found to be effective in personal care products as well.
BHA is derived from an aromatic compound called anisole, found in essential oils like anise and fennel.
Homosalate is an oil-soluble chemical sun-blocking agent that absorbs UVB radiation. It’s commonly used in formulations of high-SPF sunscreen products.
Benzyl alcohol is an aromatic alcohol with a light floral scent. It has various beneficial properties and is commonly added to cosmetics and personal care products.
