Parents and residents around the plant have voiced their anger over the incident, which marks the second case of poisoning this week.

"We used to recruit several hundred children every year but parents have stopped sending their children here this summer," a local kindergarten teacher told Xinhua.

"Who knows, maybe our classrooms will all be empty when the new term begins next month."

Angry protests

Al Jazeera's Melissa Chan, reporting from Beijing, said industrial pollution is becoming a "chronic problem" for China.

Even though China has had a greater awareness of the need to be more environmentally conscious, the country is still seeing cases such as these, Chan said.

"Officials are concerned not just in the sense that it affects the people," she said.

"They are also concerned about the violence that can flare up in cities when villagers find out that their health has been affected."

Earlier this week, hundreds of villagers whose children were affected by the leaching of lead from a local smelter stormed the Dongling Lead and Zinc Smelting Co plant in Changqing town.

The villagers also tore down fences and blocked traffic outside the factory in protest.

About 80 per cent of the children in two villages near the plant had tested positive for lead poisoning, some of them with lead levels 10 times the level considered safe in China.

A senior city official later apologised for the incident.

Authorities shut down the factory on Tuesday citing safety reasons, following protests in the latest sign of growing anger over the country's rampant industrial pollution.

Contamination

Lead poisoning can damage the nervous and reproductive systems and cause high blood pressure, anaemia and memory loss.

It is especially harmful to young children, pregnant women and foetuses, and the damage is usually irreversible, according to the World Health Organisation.

Following the outrage, authorities promised to relocate hundreds of families within two years with the building of new homes about 5km from the plant starting last week, but residents were not reassured.

Parents of more than 600 children found excessive levels of lead in their blood [AFP]
Deng Xiaoyan, a farmer in Sunjianantou, one of the affected villages, said a recent test showed her three-year-old daughter had high levels of lead.

"If they relocate us to these nearby places, who can guarantee that our babies will be safe?" she said.

She said she thought those houses would still be too close.

"There is lead in the air, the air is polluted, everything is polluted," she said.

China's pollution and lax product safety standards have long been a source of tension and unrest, particularly when residents of pollution hotspots - dubbed "cancer villages" because of high disease rates - feel they are being ignored.