A recent meeting held under United Nations auspices agreed on a treaty
to phase out and eventually ban a number of toxic chemicals. As the
Financial Times reported (December 10) the 600 delegates gathered in
Johannesburg gave their assent to ban 12 long-lasting chemicals known as
persistent organic pollutants, or Pops. These include pesticides,
industrial chemicals and by-products of combustion.

However DDT, a substance used in the fight against malaria, has been
exempted until a cost-effective and environmentally friendly alternative
can be found. It is the first time, noted the report, that governments
have acted on a world-wide basis to ban toxic chemicals.

Developed countries have pledged to provide financial and technical
assistance to developing nations to assist in the elimination of toxic
chemicals. The existing Global Environment Facility will be used to
channel the funds. Although developing countries originally wanted a
mandatory special fund, they consented to a compromise.

The treaty will be formally signed in May 2001 in Stockholm and
individual countries will then be expected to ratify it, to develop
national action plans and to report regularly on their progress. At
least 50 countries are required to ratify the treaty before it comes
into force.

DDT prohibited by rich countries

According to the Economist (December 16) the decision to allow continued
use of DDT represents a victory for common sense. The magazine pointed
out that for rich people malaria is not much of a problem as the
Anopheles mosquito, which spreads the disease, was eradicated from
Europe and North America half a century ago, largely through the use of
pesticides such as DDT.

However, at that point, having used DDT to eliminate these insects rich
countries then banned it. The problem came, explains the Economist, when
many rich countries tried to impose their decision on the poor world,
where about 300m people suffer from malaria every year, and more than a
million die. Jeffrey Sachs, a development economist at Harvard
University, estimates that sub-Saharan Africa would be almost a third
richer today had the disease been eradicated in 1965.

An article published by the British paper, the Independent (December 3)
put the number of fatalities due to malaria even higher. The paper
affirmed that the mosquito-borne parasite is said to kill 200 children
under the age of five every hour in the developing world and up to 2.5
million Africans every year.

The most cost-effective way of fighting malaria is to spray the insides
of houses with DDT. This either kills the mosquitoes, or drives them
away. The recommended alternatives, pyrethroids, are four times as
expensive as DDT and also less effective.

The widespread use of DDT in the 1950s and 1960s all but eliminated
malaria in several developing countries and saved an estimated 500m
lives by 1970. Since then, its use has shrunk. Of the roughly 100
countries where malaria is endemic, only 23 now employ DDT. This is
frequently the fault of aid donors who help to finance the battle
against malaria.

According to the Economist in the early 1990s, for example, the United
States Agency for International Development stopped the governments of
Bolivia and Belize from using DDT. In Madagascar, the United Nations
Development Programme tried to persuade the government to replace DDT
with Propoxur, a less effective pesticide. In Mozambique, both NORAD,
the Norwegian development agency, and SIDA, its Swedish counterpart,
said that they could not support the use of DDT, as it was banned in
their own countries.

DDT defended

However there are many experts who defend the use of DDT in the fight
against malaria. According to the October issue of Environment and
Climate News two articles in the July 29 issue of The Lancet, a
respected British medical journal, made a passionate case for DDT.

In the Lancet article, "DDT House Spraying and Re-emerging Malaria,"
Donald R. Roberts and colleagues from the Uniformed Services University
of the Health Sciences in Bethesda, Maryland described the degree to
which malaria cases are increasing, and at an accelerating rate, in
Africa. The investigators also recounted how malaria is now reappearing
in areas from which it had been eradicated, including Korea and central
Asia.

Even with the current patchwork application of DDT in epidemic areas,
malaria rates are starting to surpass those last seen in the 1940s,
affecting additional millions of infants, children, and adults. No
public health program without DDT will stop the progression of global
malaria.

The authors point out that "claims of risks of DDT to human health and
the environment have not been confirmed by replicated scientific
inquiry," and they quote World Health Organization documents that "have
consistently and accurately characterized DDT-sprayed houses as the most
cost effective and safe approach to malaria control."

In the second Lancet article, titled "How Toxic Is DDT?" A.G. Smith of
Leicester University, United Kingdom, states DDT is safer than many
other chemical insecticides. Even in DDT-sprayers and occupants of
DDT-sprayed households, Smith notes, "associated toxicity has not been
found."

Just prior to the UN meeting the British Medical Journal (December 2)
published a debate on the use of DDT. Arguing in favor of its use was
Amir Attaran, director of international health research at the Center
for International Development of Harvard University.

Attaran noted that the campaign to ban DDT, joined by 260 environmental
groups, reads like a who's who of the environmental movement and
includes names such as Greenpeace, Worldwide Fund for Nature (WWF), and
the Physicians for Social Responsibility. However the Harvard expert
considers that "This view is stunningly naive".

Attaran explained that DDT residual house spraying is an inexpensive,
highly effective, practice against malaria, and it has been approved by
the World Health Organization. In this procedure trained sprayers apply
a small quantity of DDT on the interior walls and eaves of homes. The
quantities involved are minimal and, unlike agricultural uses which
inject tonnes of DDT into the outdoors, indoor house spraying results in
little harmful release to the environment. In fact, the article explains
that for the amount of DDT used on a cotton field, all the high risk
residents of a small country can be protected from malaria.

If DDT can be this successful, why ban it, asked Attaran. He explained
that the latest campaign stems from charges that DDT is an "endocrine
disrupter" whose ability to cause harm is both indiscriminate and vast.
The World Wildlife Fund and Physicians for Social Responsibility indict
DDT chillingly: as a carcinogen, a teratogen, an immunosupressant, and
so on.

These accusations, according to the British Medical Journal article,
cannot be sustained.  Attaran observed that conspicuously absent behind
the campaigners claims are any epidemiological studies to demonstrate
adverse health effects. Even though hundreds of millions of people have
been exposed to raised concentrations of DDT through occupational or
residential exposure from house spraying, the literature has not even
one peer reviewed, independently replicated study linking exposure to
DDT with any adverse health outcome.

The article concludes with an affirmation that the public health
benefits of DDT amply outweigh its health risks, if indeed such risks
exist at all. The decision to allow its continued use is indeed, a
victory for common sense.