24 June 1998

The new Protocol on Persistent Organic Pollutants to the Convention on

Long-range Transboundary Air Pollution

WHAT ARE PERSISTENT ORGANIC POLLUTANTS?

When an organic substance possesses a combination of important properties it is said to be a persistent organic pollutant (POP). These properties are:

• Toxicity: POPs have been associated with a wide range of effects in wildlife, including birth and developmental abnormalities, cancers, and reduced immunological function leading to reduced resistance to infections. Some are also known to disrupt the endocrine system. In humans, similar effects are thought to occur. The main concern is for effects resulting from chronic exposure to quite low concentrations over a long period of time rather than from acute poisonings following accidents.

• Persistence: POPs are very resistant to breakdown, both in the physical environment and when they have been taken up by plants and animals. Therefore, once they have been released to the environment, they will be there for a long time.

• Bioaccumulation and often biomagnification: Plants and animals absorb POPs from water or their food much more efficiently than they can excrete them, resulting in a steady increase in contamination over their lifetime. This is known as bioaccumulation. Similarly, animals which eat other animals accumulate all of the POPs taken in over the lifespans of all their prey. This process, which is known as biomagnification, can deliver remarkably high concentrations of some POPs to top predators even if the levels in the surrounding physical environment (such as sea water) are quite low. For example, biomagnification in the Arctic can lead to a 1 billion magnification from water to top predators (such as polar bear or Inuit people feeding on traditional marine foods). When this occurs, the chemical burdens, built up over a lifetime, are passed to young via the egg (in the case of birds) or through the placenta and breast milk (in mammals).

• Migration over long distances from their source: POPs tend to pass easily into the atmosphere when they are exposed to the environment. Once in the atmosphere they can travel long distances very quickly and are, therefore, found all over the world, regardless of where they are used. The ability of most POPs to remain in the atmosphere decreases whenever the atmosphere becomes colder, when they condense back to the Earth=s surface. They may therefore cycle into and out of the atmosphere by what is called a Agrasshopper effect@, but ultimately they are thought to accumulate in cold regions. The oceans, lakes and soils are huge reservoirs of previously released POPs.

Are high concentrations of POPs found everywhere?

Although it is difficult to generalize, environmental and health authorities are most concerned about POPs in two types of circumstances where the properties of POPs have led to high levels in some top predator species. The first is in areas with a hinterland history of high POP release such as the Baltic, North Sea, Mediterranean Sea, and the Great Lakes of North America. For example, in the Great Lakes, studies of children indicate a variety of developmental and cognitive effects associated with exposure in the placenta to PCBs derived ultimately from the mothers= food. The second is in regions where the properties of POPs alone, with no significant local sources, are responsible for the occurrence of similarly high levels. For example, in some of the Arctic marine species, which are a significant part of the diet of indigenous people, biomagnification and other ecological and life-cycle factors are responsible for the levels of POPs, which are of concern to health authorities.

Where do POPs come from?

Most POPs are man-made. Examples include some industrial substances such as PCBs, many first-generation pesticides, including DDT, Chlordane, and Toxaphene, and several unintentionally produced substances, such as Dioxins, Furans, and PAHs, which result from the combustion of a wide range of common substances and materials.

What will the POPs Protocol do?

Because the primary mode of rapid dispersal of POPs around the world is through the atmosphere, the Convention on Long-range Transboundary Air Pollution is the ideal instrument to initiate international cooperation to control these substances. The basic obligations of the Protocol stipulate a wide range of actions ranging from production and use bans and phase-outs, restricted uses and emission controls, and conditions for the disposal of POPs. The Protocol has been designed to stand the test of time by incorporating the ability to modify the list of substances controlled or the actions taken (including adding substances) without it being necessary to renegotiate the entire Protocol. The 16 substances included in the present Protocol are:

Pesticides - Aldrin, Chlordecone, Chlordane, DDT, Dieldrin, Endrin, Heptachlor, Hexachlorocyclohexane, Mirex, and Toxaphene;

Industrial chemicals - Hexachlorobenzene, Hexabromobiphenyl and PCBs;

Unintended byproducts - Dioxins, Furans, and PAHs.

Where will these actions be in effect?

The Convention covers 42 countries in the northern hemisphere and the European Community, all of which will be free to sign the POPs Protocol. Many studies have indicated the presence of important sources of POPs within this area. On 29 June 1998 an intergovernmental negotiating committee will meet in Montreal (Canada) to begin the preparation of a global agreement on POPs following decisions of the Governing Council of the United Nations Environment Programme, and the World Health Assembly. The initial focus will be on twelve specified POPs, all of which are included in the present POPs Protocol to the Convention. Many activities are underway to ensure that the UN/ECE experience is available for the global negotiations. The ultimate aim is to take action against POPs worldwide.

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