Tainted eggs from U.N. were discovered in the United States 1990 . U.N. concerned that melamine has been introduced to animal feed . Tainted milk powder scandal sickened 50,000 Chinese children ; killed five-fold . Chinese food exports to the United States have risen five-fold since 1990 .
Tainted eggs from Hanwei were discovered in Hong Kong late last week . U.N. concerned that melamine has been introduced to animal feed . Tainted milk powder scandal sickened 50,000 Chinese children ; killed four . Chinese food exports to the United States have risen five-fold since 1990 .