The local government organized a sample investigation in October, checking the level of lead in the blood of 24 children, and the result showed that, in 87.5 percent of the children, lead levels had decreased, according to Liu Ren.

"There are three children whose lead level did not decrease at all, even though the nutrition intervention measures have been taken for more than three months," Liu said.

Chen Fameng, a 37-year-old man of Yuling township whose 5-year-old daughter was found to have excessive lead in her blood in July, said that the lead level in his daughter's blood has decreased following the treatment provided by the government.

"My baby girl developed the symptoms of epilepsy as early as in 2009, at the age of 2, and I did not know it was caused by the excessive lead in the blood," he told China Daily. "The test result showed that the lead level in her blood was more than three times higher than normal."

The lead level in the blood of Chen's daughter had decreased by nearly 30 percent at the end of October, according to a report made by a hospital in Xi'an, capital of neighboring Shaanxi province.

It's difficult for the patients to expel all of the lead from their blood, and it usually takes a decade to expel half the lead from the human body, Liu said.

"What we are continuing to do is to conduct the nutrition intervention plan and tell the children to form healthy habits in daily life, for example, to wash their hands before eating, to clean their toys, and not to nibble pencils," Liu said.

For villagers still being exposed in the lead-contaminated regions, the most important thing is to move to a safer place at least 2 kilometers away from the lead factory, according to Liu.

However, not all of the villagers agreed to move, since most of them have to move their ancestors' tombs.

"Chinese people believe that people should be left in peace after they are buried," Zhao Tie'an said.

"As a matter of fact, I had to beg the villagers many times to move their families' tombs and once I had to hire a fortune teller to persuade a villager to move his family's tombs."

It is not known when the three lead factories will restart production, even though the investors have already suffered considerable economic losses.

Chen Youjun, 54, who has invested more than 40 million yuan in the lead factory in Yuling township, said that he has had to hide from time to time because many creditors come to ask for their money back.

"I have to pay the bank at least 60,000 yuan in loan interest every month since the lead factory stopped production last July," Chen told China Daily. "I almost want to commit suicide."

Feng Xiaolong said that the lead plants should be restarted on condition that all of the residents have moved out of the polluted region and the lead plants have passed inspection by the environmental authorities.

"We will not gain economic progress at the expense of our people's health," he said.