Butylated hydroxytoluene

Butylated hydroxytoluene (BHT) is a derivative of cresol, an aromatic organic compound in which two additional hydrogenatoms in the benzene ring are replaced by tertiary butyl groups. Its technical name is 2, 6-di-tert-butyl-p-cresol. In its pure form BHT is a white crystalline solid with a melting point of 158°F (70°C) and a boiling point of 509°F (265°C). It is normally insoluble in water, but for commercial applications, it can be converted to a soluble form.

BHT was first used as an antioxidant food additive in 1954. An antioxidant is a substance that prevents the oxidation of materials with which it occurs. BHT, therefore, prevents the spoilage of food to which it is added.

BHT has grown to be very popular among food processors and is now used in a great range of products that include breakfast cereals, chewing gum, dried potato flakes, enriched rice, potato chips, candy, sausages, freeze-dried meats, and other foods containing fats and oils. BHT is sometimes used in conjunction with a related compound, butylated hydroxyanisole (BHA) as a food additive.

Some evidence exists that BHT may be harmful to human health. Studies suggest that the compound may damage the liver and kidneys. However, the U.S. Food and Drug Administration has deemed that BHT is safe enough when used in limited concentrations. It currently permits its use in concentrations of about 0.01% to 0.02% in most foods. As an emulsion stabilizer in shortening, it may be used in a somewhat higher concentration, 200 parts per million. Some authorities suggest that BHT poses too large a health risk and that it should be banned in foods. That policy has been adopted in some other nations, such as England and Australia, where its use is permitted as a food additive only in special cases.

BHT does have other commercial uses, as in animal feeds and in the manufacture of synthetic rubber and plastics, where it also acts as an antioxidant.

See also Food preservation.