In 1998, USDA commissioned the Harvard Center for Risk Analysis to conduct an analysis and evaluation of the U.S. regulatory measures to prevent the spread of BSE in the U.S. and to reduce the potential exposure of U.S. consumers to BSE. The Harvard study concluded that, if introduced, due to the preventive measures currently in place in the U.S., BSE is extremely unlikely to become established in the United States. FDA and other Federal agencies have been vigilant in strengthening protective measures to reduce the U.S. consumer's risk of exposure to BSE-contaminated food and cosmetic products. Since 1989, USDA has banned imports of live ruminants, such as cattle, sheep and goats, and most products from these animals from countries known to have BSE. Subsequently, USDA expanded this ban to include both countries with BSE and countries at risk for BSE. In 1997, FDA prohibited, with some exceptions, the use of protein derived from mammalian tissues in animal feed intended for cows and other ruminants. See the FDA/CVM website at www.fda.gov/cvm for information on the "ruminant feed ban." On Jan. 8, 2004, the USDA's Food Safety and Inspection Service issued new rules to enhance safeguards against BSE. Details on these rules may be found at USDA's website, www.usda.gov. Also in 2004, FDA issued a rule that prohibits the use of certain cattle material, because of the risk of BSE, in human food and cosmetics. Source: http://www.cfsan.fda.gov/~comm/bsefaq.html