China tightens rules on US pork

US pork exporters are coping with a requirement from China, their third-biggest international market, that the products they ship be verified as not containing the additive ractopamine.

The rule took effect on March 1, China's General Administration of Quality Supervision, Inspection and Quarantine announced.

Ractopamine is an additive fed to US-raised swine to produce leaner meat. It is a beta-agonist, a class of substances that studies have found to cause side effects in humans such as anxiety, high blood pressure and increased heart rate. China has banned beta-agonists in animal feed and animal products since 2011, after people became sick in incidents traced back to ractopamine.