tert-butyl-4-hydroxyanisole (1,1-dimethylethyl)-4-methoxyphenol tert-butyl-4-methoxyphenol
Butylated hydroxyanisole (BHA) is an antioxidant consisting of a mixture of two isomeric organic compounds, 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole. It is prepared from 4-methoxyphenol and isobutylene. It is a waxy solid used in certain amounts as a food additive with the E number E320. The primary use for BHA is as an antioxidant and preservative in food, food packaging, animal feed, and cosmetics, and in rubber and petroleum products. BHA also is commonly used in medicines, such as isotretinoin (known as Accutane/Roaccutane), lovastatin, and simvastatin, among others.
Since 1947, BHA has been added to edible fats and fat-containing foods for its antioxidant properties as it prevents food from becoming rancid and developing objectionable odors. Like butylated hydroxytoluene (BHT), the conjugated aromatic ring of BHA is able to stabilize free radicals, sequestering them. By acting as free radical scavengers, further free radical reactions are prevented.
Some controversy surrounds the use of BHA in foods. The US National Institutes of Health report that BHA is reasonably anticipated to be a human carcinogen based on evidence of carcinogenicity in experimental animals. In particular, when administered as part of their diet, BHA causes papillomas and squamous cell carcinomas of the forestomach in rats and Syrian golden hamsters. That said, when examining human population statistics, the usual low intake levels of BHA shows no significant association with an increased risk of cancer. The State of California, has, however, listed it as a carcinogen. Furthermore, the acceptable daily intake (ADI) of BHA and a similar preservative, butylated hydroxytoluene BHT, is exceeded by only a small fraction of the population.
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