Two weeks after the U.S. cracked down on China’s shrimp and catfish for containing traces of antibiotics, China fired back, banning meat products from seven U.S. companies, including two that sold pork ribs and pig ears containing residues of a chemical called ractopamine.

Ractopamine?

From the Post article:

“It’s fed to a large majority of the pigs in the United States,” said Jim Hodges, president of the American Meat Institute Foundation. “It simply results in more high-quality, lean pork and less fat.”

…AND some stressed-out piggies. From a USDA study:

[Use of] ractopamine has been…accompanied by…reports of effects on the behavior of the pigs, making them ‘hyperactive’ and more susceptible to transport stress…At the end of the 4-week study, [ractopamine-treated pigs] had higher heart rates than control-fed pigs and higher levels of circulating stress hormones.

Ractopamine is a beta agonist, a class of chemical that includes drugs used to treat asthma and premature labor. One of the beta agonists, clenbuterol, has been in the news lately since it’s been used to make women look more like Paris Hilton, weightlifters more buff, and pork meatier:

A total of 336 people have been poisoned in Shanghai since September 13 [2006], in the city’s largest clenbuterol poisoning case. The chemical can reportedly cause damage to the human nervous and cardiovascular system…Most of the pigs have been traced to neighboring Zhejiang where rearing pigs on clenbuterol, known locally as “lean meat powder”, is widespread.

Which might explain why China has not joined the 23 countries—including the U.S., Canada, Australia, Brazil, and Mexico (but not Europe)—who have approved the related chemical, ractopamine, for use in food production.

Whatever else might emerge from the Great Imported Food Scandal and Trade War of 2007, we certainly are learning a lot about what on earth we are eating.