Animals older than 30 months old are considered at a greater risk for mad cow disease , which can be transmitted to humans . Tens of thousands of South Koreans opposed imports of U.S. beef . With imports largely banned since 1972 when mad cow disease found in U.S . Protests essentially paralyzed the government of President Lee Myung - bak .
Tens of thousands of South Koreans opposed imports of U.S. beef . With imports largely banned since 1972 when mad cow disease found in U.S . Protests essentially paralyzed the government of President Lee Myung - bak .