This marks the start of hard effort to rid the w orld's most populous country of highly dangerous pesticides and other hazardous chemicals.

"China will take every necessary measure to fully implement the convention, as it is beneficial not only to the sustainable development of China but also to that of the world," said Wang Jirong, vice minister of the State Environmental Protection Administration(SEPA).

However, he acknowledged that it is extremely hard work, as thecountry is fighting severe traditional environmental problems suchas water pollution, acid rain and urban air pollution nationwide. Also, China lacks technology, sufficient funds and even laws to effectively tackle POPs.

Of all the pollutants released into the environment every year by human activity, POPs are among the most dangerous. They are highly toxic, causing an array of adverse effects, notably death, disease, and birth defects, among humans and animals. Specific effects can include cancer, allergies and hypersensitivity, damageto the central and peripheral nervous systems, reproductive disorders, and disruption of the immune system.

According to the United Nations Environment Program, every humanin the world carries traces of POPs in his or her body. POPs are highly stable compounds that can last for years or decades before breaking down. They circulate globally through a process known as the"grasshopper effect."

To deal with the global problem, a convention on POPs was passed at a meeting in Stockholm, Sweden, in May 2001, and has been signed by 151 countries and ratified by 83 countries including China.

The treaty requires that all parties to take necessary steps to ban the production and use of some of the most toxic chemicals.

The 12 initial POPs are aldrin, chlordane, DDT, dieldrin, endrin, heptachlor, mirex, toxaphene, polychlorinated biphenols(PCBs), hexachlorobenzene(HCB), dioxins and furans.

Fortunately, there are alternatives to most POPs. The problem has been that high costs, a lack of public awareness, and the absence of appropriate infrastructure and technology have often prevented their adoption.

This is specially true in China.

Of all the nine pesticides in the initial list, four are still produced and used in China, including DDT, HCB, Chlordane and mirex.

A large amount of discarded PCBs, which are mainly used in electric appliances and production of paints, has not been disposed of effectively and leaking has been reported in some storage sites causing serious pollution.

Meanwhile, pollution of dioxins and furans generated in such processes as paper-making, metal production and waste incinerationis also significant, as the country's economy grows at a high speed.

"China can produce some alternatives to POPs, but farmers or enterprises are reluctant to use them, because the prices are too high," said Zhang Qingfeng, an official of SEPA.

And it is also very difficult to make a list of or locate thesources of POPs, he said, estimating that it could cost at least 400 million US dollars to get a clear picture of POPs in the country.

Another major challenge is the lack of public awareness, because most people in the country have little knowledge of what POPs are, he said.

"Despite the challenges, China will firmly go ahead with the adoption of the Stockholm convention," Wang said, adding that a number of institutions for the purpose had been set up, includingthe Steering Group for Compilation of China National Implementation Plan that consists of SEPA and 10 other government departments.

He called for more international support in terms of funds andtechnologies to help the largest developing country in the world fulfill the obligations designated in the convention.