Authorities in south China's Guangdong Province have dismissed parents' claims that a battery manufacturing plant was responsible for the lead poisoning of at least 10 children.

Medical tests taken on Dec. 31, 2009 have shown 10 out of 33 children, aged from 2 to 12, in the second village of Xingren Community, Shijiao Town, Qingyuan City, had excessive levels of lead in their blood.

The most serious case was Luo Zhicheng, an 11-year-old girl, with a blood lead level at 213 micrograms of lead per liter of blood.

The other nine children had blood lead levels ranging from 100 to 199 micrograms of lead per liter of blood, proving mild exposure to lead.

Villagers blame Weierdun Industrial Co., Ltd, a battery manufacturer.

"I often see black smoke spiraling from the battery factory and it is very smelly. We don't dare to leave our doors open," said Lin Bingqun, a villager living near the plant.

Villagers have video footage of used batteries piled on the factory's floor. The piles have since been moved and the battery factory has suspended its operations.

"The batteries we produce don't contain lead," said Li Zhenrong, manager of the factory. "I admit that we didn't dispose of the used batteries very well but we are working on that."

His assessment was echoed by the Qingyuan City Environmental Protection Bureau.

Lead poisoning could be caused by several factors, such as inhaling too much automobile exhaust, said Zhang Xiaofeng, a Qingyuan Environmental Protection Bureau official.

"We will further investigate the cause of the poisoning," said Zhang.

Too much lead can damage various systems of the body including the nervous and reproductive systems and the kidneys, and it can cause high blood pressure or anemia. High blood lead levels in children can cause consequences which may be irreversible including learning disabilities, behavioral problems, and mental retardation. At very high levels, lead can cause convulsions, coma and death, says a document available on the website of World Health Organization.