Residents fled a county in central China at the weekend over rumors of a radiation leak at a factory but most returned yesterday after local government issued assurances that it was safe.

The exodus was sparked last Friday when bystanders saw government workers using robots to examine a cobalt-60 irradiator that had malfunctioned at a factory in Qixian County, Henan Province.

The irradiator is used mainly for sterilizing pepper powder, a flavoring used in instant noodles and garlic.

"There was chaos on the streets from about 2:30 pm until dark," Zhu Zhihai, manager of a factory that processes garlic, said yesterday. "All kinds of vehicles were going out of the county - farm vehicles, motorcycles and cars."

He estimated that about a third of the population of about 1 million in Qixian County fled, many because they had heard rumors that there had been explosions.

Some people fled as far as Henan's capital city of Zhengzhou, about 100 kilometers away.

Some parents were keeping their children away for a few more weeks, according to local residents.

"People were in a hurry and they didn't take anything with them. The public security bureau kept trying to persuade them not to leave," said Zhu, adding that his 30 employees also left.

He said he didn't leave because his friends at the local environmental protection bureau told him the rumors of a disaster were untrue.

Li Chunsheng, deputy director of the Environmental Protection Bureau of Kaifeng, which oversees Qixian County, said in a statement posted on the government Website on Saturday that the irradiator problem "will not cause any harm to the public."

He said the cobalt-60 is stable and would not explode or emit radioactive gas.

Li said the irradiator malfunctioned on June 7 when its protective shield was knocked askew while a batch of peppers was being sterilized.

As a result, the device could not be put properly into its storage well, Li said.

The irradiator, which is operated by remote control, was in a sealed room secured with concrete and two layers of stainless steel, according to Li. Daily inspections since have shown no leaks, he said.

According to the United States Environmental Protection Agency says cobalt-60 is increasingly used for sterilization of spices and that exposure to gamma radiation directly from cobalt-60 can increase a person's cancer risk.

(Shanghai Daily July 21, 2009)