FENGXIAN, China (Reuters) - Chinese provinces have begun shutting lead smelters for environmental checks, after hundreds of children tested for high levels of lead in two separate cases this month.

Residents walk past a zinc smelter belonging to the Dongling Group, in Fengxian county, Shaanxi province, August 22, 2009. A lead smelter belonging to the same group was closed this month after nearby children were found with high levels of lead in their blood, a problem that is endemic in communities near smelters across China. REUTERS/Lucy Hornby

At least three lead smelters in Henan province and two in Shaanxi province, with a combined capacity of about 6 percent of China’s annual production, were ordered to temporarily halt operations in recent days, officials said.

The closures came after parents protested at a lead and zinc smelter operated by Dongling Group in Changqing, Shaanxi Province, and at a manganese smelter in Hunan this month.

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.

Lead poisoning is endemic among villages near Chinese smelters, interviews conducted this weekend showed.

In Shaanxi’s Fengxian, where smoke billows from a Dongling Group zinc smelter, two wan and listless toddlers tested with high levels of lead in their blood earlier this year. Villagers requested but did not get testing for 30 other children.

“These problems are really common actually. It’s just that the Dongling case in Changqing got some attention,” said a villager surnamed Tu. Older villagers developed circulatory problems and some workers at the plant got too sick to work.

“This environmental pollution is not unique to Fengxian. It’s all over.”

Lead poisoning due to air and water pollution from poorly regulated smelters and mines haunts the valleys of the ore-rich Qinling range, in a poor and remote part of China.

The problem dogs heavy metals bases in Hunan, Henan, Yunnan and Guangdong provinces. Closing polluting plants has pushed the industry to poorer areas where any investment is welcome.

The shift to poorer regions echoes the migration of the lead smelting industry to China over the last decade, as stricter environmental laws forced smelters in richer countries to close.

China’s output of refined lead rose nearly 20 percent in 2008 to 3.26 million metric tons. Output feeds the Chinese battery industry, the world’s largest, which then exports worldwide.

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The casualties of China’s heavy metals industry only get attention when officials respond to cases too large to ignore.

In late 2005, two of China’s largest zinc smelters shut temporarily after cadmium contaminated the Pearl River Delta and the Xiang River, sources of drinking water for millions in Hunan and Guangdong Provinces. Cadmium hurts kidney and lung function.

Elevated cadmium levels also showed up in tests of children near the Dongling Group’s lead and zinc smelter in Changqing.

Children are most vulnerable to lead poisoning because they are still developing, but smelter workers also fall sick because they absorb it through their skin. Ingestion of large amounts of lead may result in anemia, muscle weakness and brain damage.

“My dad couldn’t stand it any more, so he quit working. It got so he could only work 20 days at a time, then he would have to stop,” said a young woman surnamed Zhang.

“Dad’s tummy would always hurt. When it’s bad, he doesn’t want to eat and has no energy.”

Zhang’s husband now works at a different smelter after her family’s employer, Shaanxi Nonferrous Metals Holding, halted work at its 50,000 ton Wenjiangsi lead smelter earlier this month.

Workers at the Wenjiangsi plant said the plant’s internal clinic regularly treats workers who get to the point that they cannot work. They resume work when they feel better.

“It’s not a problem if you drink a lot of alcohol,” said a young man in a blue work uniform.