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HEALTH-LATIN AMERICA: Much-Maligned DDT Still Has Supporters

Diego Cevallos* - Tierramérica

MEXICO CITY, May 3 2005 (IPS) - DDT is one of the 12 substances known as persistent organic pollutants that the international community has targeted for urgent elimination. But this insecticide, which before falling out of favour prevented millions of deaths and inspired a Nobel Prize, may yet 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 Organisation (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 Centre, 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 authorises DDT use exclusively for fighting the vectors of diseases, under the guidelines of the World Health Organisation.

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 Programme (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 has weighed in on the issue as well, saying that 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 vector mosquitoes, it will be many years before DDT is completely eliminated.

Every year a total of 7,500 tonnes 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 the Convention 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 utilise 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 authorisation 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 authorisation to renew use.

However, reports from UNEP and from the non-governmental RAP-AL, a Latin American 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 programme, 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 tonnes 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.

(* With reporting by Juan Carlos Frías in Ecuador, Humberto Márquez in Venezuela and Jorge A. Grochembake in Guatemala. Originally published Apr. 30 by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme and the United Nations Environment Programme.)