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Butylated hydroxytoluene (BHT) consists of a synthetic preservative used in the food, plastic, and petroleum industries. A white, crystallized molecule, BHT antioxidant prevents oxidation of rubber, resins, and plastic while preserving color. BHT antioxidant added to food and food packaging preserves aroma, color, and freshness. It commonly exists in foods containing fat to prevent it from becoming rancid.
BHT is also approved by health and safety agencies for use in animal feed to preserve vitamin content and taste. One study found adding BHT antioxidant to chicken feed prevented Newcastle disease, a viral infection that causes death in poultry. This study prompted researchers to theorize BHT antioxidants might prevent viruses in humans. Some people use BHT antioxidants to treat simplex herpes, but no human trials prove its effectiveness.
One animal study showed the antioxidant impaired the blood’s ability to clot and led to tumors when used over a long period of time at high doses. Researchers found anti-carcinogenic properties in BHT antioxidants in lower doses. They concluded the amounts found in food are likely harmless.
Products made with polypropylene resin must be manufactured at high temperatures, causing the resin to degrade and become brittle. Adding BHT antioxidant to the mixture stabilizes the resin and preserves color. It produces similar effects on waxes, rubber, and plastic. Most plastic food containers and food wraps contain this additive.
The preservative is also found in many hydraulic oils, brake fluids, transmission fluids, and cutting oils to prevent them from gumming up. Oil used to treat leather, along with other materials subject to fatty, waxy, or greasy coatings, can be stabilized with the preservative. BHT manufacturers typically sell the additive in crystal form, as pellets, or liquids blended with oils.
Food items, like potato flakes and dry cereals, typically contain the additive. It might also be added to pasteboard food cartons and plastic bags inside the boxes to help packaging materials last longer on the shelf. BHT is typically used in combination with butylated hydroxyanisole(BHA)antioxidants, citric acid, and other preservatives. It also helps chewing gum retain its elastic properties.
In the rubber industry, colorless products benefit from this additive because it does not stain. If products are black, such as tires, another preservative can be used without fear of stains. Manufacturers who use large quantities of the preservative for molten use commonly purchase it in liquid form.