The consumption of offal and meat tainted by clenbuterol can cause dizziness, headaches, hand tremors, palpitations, agitation and other symptoms. The greatest risks are posed to those who have heart troubles, experts said.

"Clenbuterol causes symptoms in several hours," said Chen Junshi, director of the Fortified Food Office under the Chinese Center for Disease Control and Prevention.

"But a small amount won't lead to poisoning. Only ingesting a large amount will."

Until the lab results come back, it will be impossible to know the cause of the food poisoning, he said.

According to a notice from Changsha's publicity department, some residents of Wufeng village, Lianhua town, Yuelu district, suffered from an accelerating heartbeat, vomiting and other discomforts after attending a wedding in the village.

The sufferers were taken to local hospitals for first aid at 8 pm on Saturday.

A China Daily reporter spoke to officials with the provincial department of health, the provincial and city centers for disease control and prevention and the town government on Sunday. But none of them had new information to report about the poisoning.

Phone calls to the city's publicity department were not answered.

Another food poisoning case happened in Yulin city, Shaanxi Province, on Friday.

At the Yuhe Central Primary School, in the city's Yuyang district, up to 251 children suffered from nausea, vomiting and other symptoms on Friday morning after drinking milk produced by the Mengniu Dairy Group.

Those students had been discharged from the hospital by Saturday.

An investigation team has been established, and the milk believed to be the cause of the tainting was set aside and sealed up so it could be put through testing to determine its contents.

The Mengniu Dairy Group said on its website on Saturday that it will help investigators determine the cause of the poisoning. It also said the milk products in the case have not harmed people other than the students who got sick.

The milk quality test report might be released on Wednesday or Thursday, according to the Beijing News.