Representatives of 122 countries meeting in Johannesburg (South Africa), including India, finalised on December 10 last the text of a legally binding treaty that would require governments to minimise and eliminate some of the most toxic chemicals ever created - chemicals that jeopardise the environment and the health of human beings and wildlife throughout the world.

The chemicals in question are known as persistent organic pollutants (POPs). They are man-made organic (carbon-containing) compounds that, being extremely difficult to break down owing to their resistance to degradation by light, chemical reactions or biological processes, have become widely dispersed through the environment - to persist for years, even decades.

Many POPs are highly toxic and accumulate over time in the fatty tissues of human beings and animals.

Occurring as POPs do in either solid or vapour form, they have a propensity to travel thousands of miles by evaporating, riding on air currents to cooler regions, condensing and settling, evaporating again when the temperature rises sufficiently and resuming their travels, and so on and so forth.

There is no clean, uncontaminated place anywhere on Earth: POP pesticides are used in the tropics; persistent combustion and manufacturing byproducts are released in temperate industrial regions; poorly-stored stockpiles of POPs leak in many parts of the world; and globehopping POPs come to rest in wild and remote places.

Fortunately, there are alternatives to most POPs. Not so fortunately, high costs, lack of public awareness and the absence of appropriate infrastructure and technology together act as a barrier to the widespread use of the alternatives.

The treaty represents the culmination of intergovernmental negotiations under the auspices of the United Nations Environment Program (UNEP) that were launched in June 1998 with the goal of concluding a legally binding global treaty on POPs before the end of 2000. The conference held in Johannesburg between December 4 and 10, 2000 was the fifth session of the Intergovernmental Negotiating Committee (INC) instituted for the purpose.

The treaty prescribes control measures that cover the production, import, export and disposal, to begin with, of 12 identified POPs that are the most widely-studied synthetic chemicals. At the same time, it envisages the establishment of a review committee that would regularly consider additions to the POPs list.

The list of 12 POPs, all of them chlorine-containing compounds that belong to a class known as organochlorines, includes eight pesticides (aldrin, chlordane, dichlorodiphenyl trichloroethane, or DDT, dieldrin, endrin, heptachlor, mirex and toxaphene), two types of industrial chemicals (polychlorinated biphenyls, or PCBs, and hexachlorobenzene) and two families of unintended byproducts (dioxins and furans) - byproducts of the manufacture, use and/or combustion of chlorine and chlorine-containing materials.

The pictures accompanying this article show, besides a scene from the Johannesburg conference, sources of dioxins and furans from open burning of rubbish/trash.

The treaty will be formally adopted and signed at a diplomatic conference in Stockholm, Sweden on May 22-23, 2001. Ratification would be the next step: the treaty will come into force as soon as 50 countries have done the needful. This process normally takes years.

The treaty is very much a matter of moment for India. According to the environmental activist group Greenpeace, chemical pesticides have been in use in India since 1949, when DDT was first imported for malaria control. Today India is among the four remaining DDT manufacturers in the world.

The use of all other POP pesticides is officially banned in India. But, says Greenpeace, at least seven tenths of the pesticides used on Indian farms belong to the 'banned' or 'severely restricted' category in industrialised countries.

India exports nearly 800,000 kg of POP pesticides a year to a large number of countries. There are also reports of such pesticides being manufactured clandestinely and exported illegally to Bangladesh and Nepal.

Not only POP pesticides but dioxins, too, are in the picture. The Government of India says that industries that engage in activities involving TCDD (the most toxic dioxin) are required to assess major hazards, adopt measures to prevent accidents and limit environmental pollution and the impairment of human health, give their workers the necessary information and prepare crisis-management plans. Greenpeace, on the other hand, says these requirements are not enforced.

In the world at large, synthetic chemicals have been produced and released in vast quantities over the past 75 years. Every person living today carries hundreds of synthetic chemicals that were not present in the bodies of the planet's inhabitants during the 19th century.

Scientists found residues of DDT in human fatty tissue in 1944. Since then , there has been mounting evidence that DDT and the other 11 priority POPs are adversely affecting children's health, behaviour and intelligence.

Here we are talking of strong circumstantial evidence. It is virtually impossible to make definitive statements about the impact of these chemicals on human health: because everybody carries a load of these substances, there is no unexposed population to study as a control group.

Over the years, several health problems have been reported in laboratory animals and wildlife exposed to one or more of the 12 POPs. They include malfunctioning of the immune system, neurological and behavioural abnormalities and reproductive disorders, the last being a manifestation of disruption of the hormone system.

During the 1980s and the early nineties, thousands of seals, porpoises and dolphins died dramatically and mysteriously in the Baltic and North Seas, the Mediterranean, the Gulf of Mexico and the North Atlantic, and off Australia's eastern coast. On the basis of scientific evidence accumulated over the past decade, it can now be surmised that damage to the immune systems of these animals as a result of exposure to DDT, PCBs and other synthetic organic compounds contributed to the 'epidemics.'

The levels of accumulation in fatty tissue of many POPs increase as one animal eats another. The highest levels are therefore found in animals at the top of the food chain, such as fish, predatory birds, mammals and human beings. Animal products - meat, fish and milk in particular - are the primary routes of human exposure to POPs.

The developing young of both wildlife and humans are the most vulnerable to the toxic effects of POPs: these substances are passed to a foetus in the womb from the mother's body and to an infant through breast milk. Of all human beings, breast-fed infants experience the heaviest exposure to POPs because these chemicals, with their affinity for fatty substances, get concentrated in breast milk.

Human beings seem to be suffering increasingly from the very health problems that have been reported in laboratory animals and wildlife exposed to POPs. There is mounting scientific evidence that the twelve priority POPs are adversely affecting children's reproductive potential as well as their ability to learn and to resist disease.

The treaty that is to be adopted next May requires governments to promote the best available technologies and practices for replacing existing POPs while preventing the development of new POPs. The governments of different countries are expected to get legislation enacted and work out action plans for meeting their treaty obligations.

The treaty provides for a financial mechanism to help developing countries and countries with economies in transition to minimise and eliminate POPs. "New and additional" funding and technical assistance are to be provided.

The agreed text of the treaty provides for certain concessions. Thus, governments will be permitted to keep using DDT for malaria control until they are in a position to replace it with cost-effective and environment-friendly alternatives.

Another concession pertains to PCBs. Though they are no longer produced, hundreds of thousands of tonnes are still in use in electrical transformers and other equipment. The treaty will permit governments to maintain existing equipment till 2025 in a way that prevents leaks.

For other POPs, several country-specific and time-bound concessions have been agreed to. The treaty commits governments to reducing releases of furans and dioxins "with the goal of their continuing minimisation and, where feasible, ultimate elimination."

Other measures the treaty requires of governments relate to reporting, research and development, monitoring and public information and education.

Click here for "POPs in the Arctic"