A banned drug called Clenbuterol is still showing up in some meat products from China, resulting in health problems such as stomach pains and heart palpitations for consumers.
Clenbuterol is known as “lean meat powder” in China because it is is fed to animals to ensure that meat will be lean. It also causes them to grow quicker.
It speeds up fat burning and muscle building, which also makes it popular with some athletes.
After three-time Tour de France winner Alberto Contador failed a drug test for last year’s competition he blamed it on steak contaminated with clenbuterol. Several other athletes have also blamed meat for positive tests.
In 2009 China’s anti-doping lab bought pork tainted with the drug, had lab workers eat it and then tested their urine. Some failed the test which would have resulted in a ban for an athlete.
ABC News reported that China’s agency advised athletes not to eat out, saying: "Our country's anti-doping testing lab has done experiments which show that eating pork meat or pork liver containing 'lean meat powder' — clenbuterol — can trigger a positive result."
Pan Chenjun, a senior industry analyst with Rabobank in Beijing, said that mass poisonings in large cities are unusual because of food inspection, but contamination is common in smaller communities.
“It's really a big problem in China,” The Globe and Mail quoted him as saying. “It's not reported frequently so people sometimes think it's not a big issue but actually it's quite widespread.”
Adding clenbuterol to pig feed results in pinker meat, so people think it is fresh for a longer period of time.
It is found in the highest concentrations in organs such as liver and lungs.
In 2006, more than 300 people in Shanghai became ill after eating meat containing the drug.
In Guangzhou in February 2009 about 70 people were poisoned by clenbuterol when they ate pig’s organs.
Thirteen people in Shenzhen, near Hong Kong, became ill after eating snakes. The reptiles had been fed frogs that were given clenbuterol.
Those caught feeding the drug to animals can often get off with a bribe.
The Globe and Mail reported that pork is China's most popular meat, with almost 50 million metric tons - about half the global supply - produced and consumed each year.
Clenbuterol is also used in both human and veterinary treatment of breathing disorders in some places.
There are companies advertising the drug for sale online and some advertising test kits to detect the drug.