In the coming 12th Five-Year Plan (2011-2015), the national environmental watchdog will launch a comprehensive national inspection program against factories discharging heavy metals and pollutants that are affecting nearby people's health.

Factories are one of the biggest contributors to global warming in several different ways.??

Zhou Shengxian, minister of environmental protection, said at the opening ceremony of the China Council for International Cooperation on Environment and Development on Wednesday in Beijing that the nation will make further efforts to solve the severe environmental problems harming people's health, such as heavy metal pollution.

The council comprises about 200 world experts who regularly offer policy suggestions to the Chinese central government.

"We will completely check enterprises discharging pollutants such as heavy metals for all potential environmental dangers. All chemical factories along rivers and lakes are in the key list," Zhou said.

Heavy metals refer to elements that exhibit metallic properties, most of which are dangerous to health or to the environment. They include mercury, cadmium, lead and chromium.

Pollutants such as heavy metals are damaging the country's land and water resources, especially under the fast economic development, environmental experts said.

In China, industrial wastewater, gas and residue are the main polluters of land and water, which will eventually pollute crops and fish.

It was estimated that every year in China more than 12 million tons of grain were polluted by heavy metals, causing direct economic losses of 20 billion yuan ($3 billion), Xinhua News Agency reported in 2006.

In 2008, the total amount of the country's industrial wastewater and domestic sewage reached 7.58 billion tons, the China Business News reported on Tuesday.

A four-year study released by the China Geological Survey in November shows only 24 percent of the underground water in the North China Plain is safe for drinking, with excessive heavy metals, overuse of chemical fertilizers and surface water pollution caused by leaking garbage dumps and sewage water irrigation the main causes of the pollution.

A metallurgical plant caused water in the middle and upper reaches of Beijiang River in South China's Guangdong province to contain excessive thallium, a kind of heavy metal, which is expected to affect the water supply in the cities of Qingyuan and Guangzhou in the lower reaches, Xinhua reported in October.

Ma Jun, director of the Institute of Public and Environmental Affairs in Beijing, said the pollution caused by heavy metals should be avoided from the outset, or it will remain in land or water for thousands of years.

Apparently, the severe land and water pollution is threatening people's health and causing many social conflicts.

The national prevention plan for key endemic diseases (2004-2010) showed, as of 2003, there were about 39 million people across the country suffering from dental fluorosis due to receiving too much fluoride during tooth development, and nearly 3 million people suffering from skeletal fluorosis. Both diseases are directly related to the local underground water containing excessive fluoride.