A long-awaited project to tackle heavy-metal pollution has been approved by the State Council as part of the 12th Five-Year Plan (2011-2015).

The national blueprint for 2015 has set an emission-reduction target for five heavy metals, in key polluted areas, by 15 percent from 2007 levels, Environment Minister Zhou Shengxian, told a televised conference on Friday.

The metals are lead, mercury, chromium, cadmium and arsenic.

There have been a number of high-profile cases involving heavy-metal poisoning in recent years.

The first national pollution census, published in 2010, shows that China discharged 900 tons of the five metals in 2007.

The ministry listed 138 target zones in 14 provinces and regions, including the Inner Mongolia autonomous region and Jiangsu and Zhejiang provinces.

A total of 4,452 enterprises, including non-ferrous metal mines, smelters, lead-acid battery manufacturers, leather producers and the chemical industry, are listed as major monitoring targets.

The list was made after an intensive nationwide survey of more than 110,000 enterprises, conducted jointly by nine ministries at the end of 2010, according to Zhou.

Provincial governments are requested to work out their specific plans and targets by the first of half of 2011. Local officials who fail to enforce the targets will be held responsible.

Zhou estimated a total of 75 billion yuan ($11.41 billion) over the next five years will be needed to address the pollution.

The breakneck expansion of heavy-metal industries, outdated technology and a lack of effective monitoring are cited as the main reasons for the pollution.

"More than 30 major heavy-metal poisoning incidents have occurred since 2009, posing a grave threat to public health, especially to children," Zhou said.

Excessive levels of heavy metal in humans can cause irreversible harm. The toxic elements accumulate in organs over time, leading to chronic disease.

Zhou said tackling violations by battery manufacturers will be a major focus this year.

In the latest case in January, more than 200 children were found with excessive concentrations of lead in their blood in Huaining county, Anhui province, the result of emissions from a nearby battery factory.

"Our investigation shows that the enterprise faked environmental review documents, and the local government's lax monitoring was also to blame," Zhou said.

As a punishment, the ministry has suspended approval for any new projects involving heavy-metal in Anqing city, which administers Huaining county.

"The blueprint shows the determination from the central government to deal with the problem, following a number of recent incidents," said Ma Jun, director of the Institute of Public and Environmental Affairs.

A recent report by Nanjing Agricultural University said research in 2007 found 10 percent of rice samples collected from markets were found to have excessive levels of cadmium.

"Unlike conventional water or air pollutants, heavy-metal pollution is usually invisible to the public, and has to be monitored with professional equipment," said Ma, "This will require an effective and sound supervisory system from local governments, as well as more public transparency on pollution data."