Now recognized by the U.S. Department of Agriculture as a potential carcinogen, sassafras is the dried root bark of the sassafras tree native to eastern North America. Throughout history, sassafras has been used for making tea, as a fragrance for soap, a painkiller, an insect repellent, and a seasoning and thickener for many Creole soups and stews.
But the best-known use of sassafras lies in the creation of root beer, which owes its characteristic flavor to sassafras extract. In 1960, the FDA banned the ingredient saffrole -- found in sassafras oil -- for use as an additive because in several experiments massive doses of sassafras oil were found to induce liver cancer in rats. It should come as no surprise that chemicals and artificial flavors are used to flavor root beer today.