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Much-Maligned DDT Still Has Supporters |
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By Diego Cevallos*
The insecticide DDT remains an effective weapon against malaria,
according to the United Nations. All indications are that the first
meeting of the Stockholm Convention on Persistent Organic Pollutants,
this week in Uruguay, will approve its continued but limited use.
MEXICO CITY - DDT is one of the 12 substances
known as persistent organic pollutants that the international community
aims to eliminate as soon as possible. But this insecticide, which
before falling out of favor prevented millions of deaths and inspired
a Nobel Prize, seems to have a long life ahead of it.
For many countries, DDT (dichloro-diphenyl-trichloroethane) is still
an ''effective and affordable'' weapon against malaria, according
to United Nations agencies.
Malaria is transmitted through mosquito bites, infecting 300 million
people worldwide each year, and killing more than a million people,
especially in Africa.
Latin America feels the impact of the disease as well. More than
a third of the region's population lives in at-risk zones, and each
year 1.4 million people, mostly children, are infected. According
to figures from the Pan-American Health Organization (PAHO), more
than 105 million dollars are spent annually to combat malaria.
Some observers attribute the devastating effect of malaria to the
limitations imposed by governments and environmentalists on the
use of DDT, a broad-spectrum insecticide, patented in 1937 by Swiss
chemist Paul Mueller.
The effectiveness and long-lasting properties of DDT prevented massive
crop losses and staved off hunger in developing countries, so much
so that Mueller won the 1948 Nobel Prize in Medicine.
But the world was put on guard against DDT in the 1970s when some
studies suggested that it is carcinogenic, leads to premature births,
contaminates food and causes neurological, respiratory and cardiovascular
harm to the human body.
Other insecticides were developed and marketed, but all were more
expensive.
''No study is conclusive about the harmful effects of DDT, but based
on the precautionary principle and the apparent pressure from some
big companies that produce insecticides (that compete with DDT)
it was agreed to limit its use,'' Américo Rodríguez, a scientist
with Mexico's Malaria Research Center, told Tierramérica.
DDT ended up on the list included in the Stockholm Convention on
Persistent Organic Pollutants (POPs), an international instrument
signed in 2001 to restrict and eliminate the use of 12 substances
worldwide. POPs have a strong tendency to accumulate in the fatty
tissue of animals and spread throughout the food chain.
The Convention authorizes DDT use exclusively for fighting the vectors
of diseases, under the guidelines of the World Health Organization.
The countries that signed the Stockholm Convention must decide if
this should continue to be the case. They have a chance to take
up the matter this week, as representatives are gathered in the
Uruguayan Atlantic resort of Punta del Este through May 6.
The United Nations Environment Program (UNEP), the driving force
behind the Convention, called for caution on the DDT question.
UNEP documents drawn up for the purpose of the Uruguay meeting indicate
that the participants could conclude that ''until safe, affordable
and effective alternatives are in place, governments can continue
using DDT to protect their citizens from malaria -- a major killer
in many tropical regions.''
UNEP executive director Klaus Toepfer was even clearer: ''Unless
more ambitious investments are made in the search for better vaccines
against the malaria parasite and better pesticides and methods for
fighting against the mosquitoes that serve as vectors, it will be
many years before the complete elimination of DDT is achieved.''
Every year a total of 7,500 tons of DDT are sprayed on the interior
walls of homes. It is a relatively cheap and effective way to repel
and kill the mosquitoes that transmit malaria.
In Latin America, several countries consider DDT their best weapon
against a potential epidemic. Ecuador, for example, will ask this
week in Punta del Este that the insecticide not be eliminated from
the market -- at least for now.
Ecuador wants to be able to utilize DDT ''at least in the next few
years,'' until the country's officials and scientists are able to
develop integral alternatives to combat malaria, Ricardo Tapia,
coordinator of the POPs project financed by the UN, told Tierramérica.
In the Andean nation, which reported 52,000 malaria cases in 2003,
DDT has not been used since 1990, but the authorities don't want
to lose the option to do so if a true health emergency were to occur.
In 2001, Venezuela and Costa Rica had requested authorization from
the UN to continue using DDT in controlling malaria mosquitoes.
Brazil, however, requested permission to use it in the production
of dicofol, a pesticide applied in citrus groves.
So far this year, Venezuela has recorded 11,000 malaria cases, but
the environmental health director at the Venezuelan Health Ministry,
Jesús Toro, said in a conversation with Tierramérica that his country
halted DDT use in 1994, and will not be seeking authorization to
renew use.
However, reports from UNEP and from the non-governmental RAP-AL,
a pesticide alternative action network, indicate that the substance
was indeed used in Venezuela in recent years.
Guatemala, meanwhile, is resoundingly opposed to application of
the insecticide. ''The use of DDT should not be permitted,'' Rodolfo
Zeissing, head of the Guatemalan Health Ministry's malaria program,
said in a Tierramérica interview.
''Guatemala's position is against DDT use because it is harmful
to the environment due to the persistence of its residues in the
soil for many years. This leads to contamination throughout the
food chain, through soil, the grass consumed by cattle, milk from
cows and human breast milk,'' he said.
In this Central American country, where more than 14,000 cases of
malaria were reported, DDT has not been used since the 1970s, according
to official sources, But NGOs say there is evidence in Guatemala,
as in many other countries in the region, of agricultural application
of the pesticide, obtained as contraband.
Some 14,500 tons of the insecticide are being stored in precarious
conditions in Guatemala, which leads some to fear an accident that
would release the toxin. Zeissing notes that support from experts
and from PAHO is necessary to eliminate DDT from his country.
Most Latin American and Caribbean governments state that in their
efforts to fight malaria they follow the recommendations of international
experts, applying a set of measures that include alternative insecticides
to DDT, sanitation supports, case follow-up, mosquito netting, community
efforts and timely medical attention.
But in the opinion of David Reyes, the RAP-AL representative in
Ecuador, that is not necessarily true. There are cases in which
health authorities are fighting the malaria vectors using ineffective
means, he said.
The impact on human health of alternative pesticides could be serious
if there are not sufficient safety controls. ''Sometimes they fumigate
right over the people. It's an outrage,'' said Reyes.
* Diego Cevallos is an IPS correspondent.
With reporting by Juan Carlos Frías (Ecuador), Humberto Márquez
(Venezuela) and Jorge A. Grochembake (Guatemala).
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