MENGXI VILLAGE, China » On a chilly evening early last month, a mob of more than 200 people gathered in this tiny eastern China village at the entrance to the Zhejiang Haijiu Battery Factory, a maker of lead-acid batteries for motorcycles and electric bikes. They shouldered through an outer brick wall, swept into the factory office and, in an outpouring of pure fury, smashed the cabinets, desks and computers inside.

News had spread that workers and villagers had been poisoned by lead emissions from the factory, which had operated for six years despite flagrant environmental violations. But the truth was even worse: 233 adults and 99 children were ultimately found to have concentrations of lead in their blood, up to seven times the level deemed safe by the Chinese government.

One of them was 3-year-old Han Tiantian, who lived just across the road from the plant. Her father, Han Zongyuan, a factory worker, said he learned in March that she had absorbed enough lead to irreversibly diminish her intellectual capacity and harm her nervous system.

"At the moment I heard the doctor say that, my heart was shattered," Han said in an interview last week. "We wanted this child to have everything. That’s why we worked this hard. That’s why we poisoned ourselves at this factory. Now it turns out the child is poisoned too. I have no words to describe how I feel."

Such scenes of heartbreak and anger have been repeated across China in recent months with the discovery of case after case of mass lead poisoning — together with instances when local governments tried to cover them up.

In the past 2 1/2 years, thousands of workers, villagers and children in at least nine of mainland China’s 31 province-level regions have been found to be suffering from toxic levels of lead exposure, mostly due to pollution from battery factories and metal smelters. The cases underscore a pattern of government neglect seen in industry after industry as China strives for headlong growth with only embryonic safeguards.

Chasing the political dividends of economic development, local officials regularly overlook environmental contamination, worker safety and dangers to public health until forced to confront them by episodes like the Haijiu factory riot.

A report by Human Rights Watch released Wednesday states that some local officials have reacted to mass poisonings by arbitrarily limiting lead testing, withholding and possibly manipulating test results, denying proper treatment to children and adults and trying to silence parents and activists.

"What we are trying to underscore is how little has been done to address the massive impact of lead pollution in China," Joe Amon, the organization’s health and human rights director, said in an interview. "It really has affected a whole generation of kids."

In more developed nations, where lead pollution has been tightly regulated for decades, a pattern of lead poisoning like China’s would most likely be deemed a public-health emergency.

High levels can damage the brain, kidney, liver, nerves and stomach and, in extreme cases, cause death. Children are particularly susceptible because they absorb lead more easily than adults.

"No blood lead level has been found to be safe for a child," Dr. Mary Jean Brown, chief of the lead poisoning prevention branch of the Centers for Disease Control and Prevention, said in an interview last week.

Chinese leaders have acknowledged that lead contamination is a grave issue and have raised the priority of reducing heavy-metal pollution in the government’s latest five-year plan, presented in March. But despite efforts to step up enforcement, including suspending production last month at a number of battery factories, the government’s response remains faltering.

At a meeting last month of China’s State Council, after yet another disclosure of mass poisoning, Prime Minister Wen Jiabao scolded Environmental Minister Zhou Shengxian for the lack of progress, according to an individual with high-level government ties who spoke on the condition of anonymity.

The government has not ordered a nationwide survey of children’s blood lead levels, so the number of children who are at risk is purely a matter of guesswork. Mass poisonings like that at the Haijiu factory typically come to light only after suspicious parents seek hospital tests, then alert neighbors or co-workers to the alarming results.

The few published studies point to a huge problem. One 2001 research paper called lead poisoning one of the most common pediatric health problems in China. A 2006 review of existing data suggested that one-third of Chinese children suffer from elevated blood lead levels.

The state Health Ministry said in 2006 that a nationwide test for children was unnecessary because their blood lead levels had been falling. But since then, a new source of lead pollution — factories that produce lead-acid batteries for electric bikes, motorcycles and cars — has emerged.

The industry has grown by 20 percent a year for the past five or six years, and is expected to expand further, according to Wang Jingzhong, vice director of the China Battery Industry Association. China now has some 2,000 factories and 1,000 battery-recycling plants. For regulators, Wang said, "It is a chaotic situation."

Enforcement is spotty at best. Shen Yulin, the environmental protection director for Deqing County, where the Haijiu factory is located, said 65 inspectors were responsible for a region of nearly 400 square miles, with more than 2,000 factories.

Haijiu breezed through six years of inspections, even though many workers say they were repeatedly hospitalized for lead poisoning. Only after last month’s protest did authorities criticize the plant for a host of violations and order the plant closed and production lines razed.

At a news conference this month, Li Ganjie, the vice minister for environmental protection, said that every suspected case of lead poisoning is fully investigated and that "the people involved, whether they are children or adults, are well-tested and treated."

Interviews over the past month with 20 families in Henan and Zhejiang provinces indicate otherwise. Near Jiyuan City, in Henan province, nearly 1,000 children from 10 villages were found to have elevated blood lead levels in 2009. Government officials ordered the children treated, families relocated and the smelters cleaned up.

But a recent visitor found children still playing in the streets of one village literally in the shadow of a privately owned lead smelter that nightly belches plumes of dark smoke. In interviews, their parents and grandparents said that local hospitals now refuse to administer new blood lead level tests, even if the families pay out of their own pockets.

"The children are not healthy. We don’t know how sick they are, and we can’t find out," said one 66-year-old villager whose two grandsons were found to have blood lead levels two and three times above the norm when tested in 2009.

Local officials appeared determined to suppress such complaints. Within a few hours of a visitor’s arrival this month, Jiyuan City’s propaganda chief appeared with three carloads of plainclothes officers, bringing all reporting and interviewing to a screeching halt.

That would not surprise Ye Cai’e, who lives near the Suji battery factory in Zhejiang province, 200 miles southeast of Mengxi. After tests showed 53 children and 120 adults suffered from excessive lead levels, Ye said that local officials said: "Whoever makes noise will not receive compensation or medical treatment."

Migrant workers and their families were also left out of the program, villagers said. Yang Fufen, 40, said her 2-year-old son tested at more than three times the allowable blood lead level in March but has received no medical attention, apparently because her legal residence is elsewhere.

At the Haiji Battery Factory, which exports to the United States, regulation of lead emissions was not so much lax as nonexistent.

The factory’s opening in 2005 brought more than 1,000 jobs. Authorities allowed the plant to expand to within a rice paddy of the village. They also ignored the breakdown of ventilation equipment and the building of a hostel for workers and their spouses and children on factory grounds.

Workers say managers simply slowed down production lines when inspectors came. One worker said he had watched a supervisor cover a device that tests for lead emissions in the air with his cap, then whisk the inspectors away for tea.

It did not take long for problems to surface. Workers said they repeatedly had tested above the occupational limit for blood lead levels and were sent to the local hospital, where drugs were injected intravenously to reduce the level and toxicity of lead in their bodies.

Zhou Zuyin, 42, said he was hospitalized for treatment of lead poisoning every year for four years, returning each time to his job of smoothing the edges of lead sheets. Even after a test revealed liver damage, he said, "The factory said it was normal."

He said his biggest worry now is his 13-year-old son’s health. A blood test showed the boy had nearly double what China considers a safe lead level.

"He is getting more and more scared," Zhou said. "I don’t know what to say to him. I just feel totally powerless."

Zhao Guogeng, vice-president of Zhejiang Haijiu Battery Co., said the company is covering the medical bills of lead victims. Authorities said the factory’s legal representative has been arrested and eight officials disciplined.

"This will never happen again," Zhang Linhua, spokesman for Deqing County, declared last week.

Maybe not there. But not three days later came a dispatch from a town 55 miles southeast of Mengxi Village: 103 children and 26 adults were found to be severely poisoned by lead pollution from tinfoil processing plants, according to China’s official Xinhua news agency. Moderately poisoned: 494.

© 2011 The New York Times Company