Moving towards a protocol: Agreement on List of Persistent Organic Pollutants (POPs)
Takes Shape in Geneva
24 January 1997
"We have reached a decisive stage in the drawing-up of a protocol on persistent
organic pollutants (POPs)," announced Mr. Lars Nordberg, Deputy Director of
the Environment and Human Settlements Division of the United Nations Economic
Commission for Europe, as the five-day meeting of the Working Group on Strategies
drew to a close on 24 January 1997 in Geneva. "It has not been easy to draw
up an initial list of POPs for inclusion in a protocol, because so many interests
are at stake." Moreover, while POPs may be harmful to human beings, some are
useful for agriculture and even for human health. "This explains why it was
necessary to use scientific arguments when discussing the need to put certain
substances on this list," continued Lars Nordberg. (See
list)
General agreement -- with one reservation -- has now been reached among the
negotiators on the following 15 POPs, which may be included in the draft protocol on
persistent organic pollutants: aldrin, chlordane, chlordecone, DDT (DDD and DDE),
dieldrin, dioxins (PCDDs), furans (PCDFs), endrin, heptachlor, hexabromobiphenyl,
hexachlorobenzene, mirex, PAHs, PCBs, and toxaphene. Short-chain chlorinated
paraffins, lindane and pentachlorophenol will require further examination before a
decision can be taken about their possible inclusion.
But what are POPs? POP stands for Persistent Organic Pollutant. POPs fall into three
broad categories: industrial chemicals (e.g. polychlorinated biphenyls or PCBs), by-products or contaminants (e.g. polycyclic aromatic hydrocarbons or PAHs), and
pesticides (e.g. DDT). POPs break down very slowly. Many tend to be fat-soluble
but not water-soluble. As a result they are easily taken in by plants, fish and other
animals but are difficult to eliminate. As POPs are semi-volatile, they can move long
distances in the atmosphere before deposition. They also 'bioaccumulate', which
means that their concentrations increase in fatty tissues. They gradually build up in
the food chain. For example, although the concentrations of a substance such as
PCBs or DDT deposited into a lake may be very low, they will be concentrated in the
fatty tissues of plankton living in the lake. Fish feeding on the plankton will further
concentrate the PCBs or DDT. This process will be repeated in fish-eating birds,
mammals and humans. Very high concentrations of these substances have long been
associated with a number of carcinogenic and other health effects. In recent years,
however, there has been a growing body of information showing that much more
subtle effects can occur at environmental concentrations which may be a result of
long-range transboundary air deposition. Some of these health effects are immune
suppression, intellectual impairment and birth effects. "That is the reason for the
development of the protocol," said Lars Nordberg.