Contaminated pork poisoned 39 people in the city of Liaoyang in northeast China's Liaoning Province on October 18.

Of those afflicted, 29 were treated at Liaoyang Emergency Center and other local hospitals for symptoms ranging from involuntary twitching to acute thirstiness. All had eaten pork bought at the same market.

Authorities confirmed the infected meat contained clenbenterol hydrochloride, a banned chemical mainly used for the treatment of asthma. It also can be used to increase the volume of lean meat in animals like pigs and chickens.

The chemical can remain in the animal's body, especially the liver and lungs, and has an adverse affect on people suffering from high blood pressure and heart disease.

This is not the first time the chemical has sickened people in China. A total of 484 residents of Heyuan in south China's Guangdong Province were poisoned by contaminated meat in 2001.

Gu Zhichun, director of agriculture for Liaoyang, told China Daily: "It is alleged that 28 pigs from the cities of Dengta and Shenyang are the source of the problem meat. Now measures have been taken to control the situation. Examinations on forage enterprises have also been undertaken to track and cut the source of the poisoned feed.

"Where the forage mixed with the chemical was acquired is still under investigation. The most likely possibility is that private pig farmers bought the chemical themselves to speed up the growth of lean meat."

Speaking of how to crack down on the illegal use of the chemical, Gu pointed out that there is still a long way to go to control the secret business among private owners. "We spend more than 100,000 yuan (US$12,000) on random checks of samplings from local forage dealers and factories every year. But private owners, driven by high profits, find various sources, which makes our job more complicated."

Only three victims of the latest poisoning are still being treated in hospital. Six others remain under medical observation, while the other 20 have been released.

(China Daily October 21, 2003)