The new Protocol on
Persistent Organic Pollutants to the Convention on Long-range
Transboundary Air Pollution
24 June 1998
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.
For more information, please
contact:
Mr Lars NORDBERG
Deputy Director
UN/ECE Environment and Human
Settlements Division
Palais des Nations, office
346
CH - 1211 Geneva 10,
Switzerland
Phone: (+41 22) 917 23 54
Fax: (+41 22) 907 01 07
E-mail: [email protected]