Chinese quality control administration said on Saturday that its local officials recently found ractopamine residue in frozen pig kidney imported from the United States and frozen pork spareribs from Canada.
Ractopamine is forbidden for use as veterinary medicine in China,
The 18.37 tons of frozen pork kidney in 1,350 cases and 24 tons of frozen pork chop in 1,600 cases were imported through the Panyu port in south China's Guangdong Province.
The local quarantine authority of Guangdong Province has returned the goods to exporters, said the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ).
According to the administration, the local authority of Guangdong has found ractopamine residue in ten batches of pork products from the U. S. and one from Canada by the end of August.
Ractopamine is a kind of adrenal stimulant, which may promote the growth of pigs and ox and help them grow more lean meat. It was forbidden for use as veterinary medicine in most of the countries across the world.
The European Union had forbidden the use of it in edible animals in a decree published in 1996, and China banned the drug in feedstuff and potable water for animals in 2002.
Only 24 countries, including the U.S., Canada and Brazil, allow the use of ractopamine in edible animals.
China previously suspended the sale of chicken feet, pig ears and other animal products from seven U.S. companies this summer, after it found the meat was contaminated with salmonella, additives and veterinary drugs.