| Policy makers need to compare the real risks that people face from malaria with the often uncertain and hypothetical risks they may face from using DDT to protect themselves from infection.
There is clear evidence that there is a close correlation between the use of DDT and reduced mortality and morbidity and no credible evidence that DDT results in harm to human health and the environment.
Governments of malaria-infested countries are therefore not justified in either preventing the use of DDT in malaria control or refraining from using it in their own malaria control programmes.
They should follow the lead of the South African government in putting real human lives saved before precautions against hypothetical and unproven risks.
Death rates on the increase
A recent paper in the leading science journal Nature estimated that every year there are 515 million episodes of malaria. Somewhere between one and two million people die of the disease every year, most of these being African children.
The worrying factor is that malaria cases and deaths have been increasing despite WHO efforts to control the disease. A key reason for the ever-increasing number of cases and deaths is that UNICEF and donors like USAID steadfastly refuse to promote anti-malaria interventions that work – such as the careful use of the insecticide environmentalists love to hate: DDT.
When used in malaria control, DDT is sprayed in tiny quantities on the inside walls of houses – a method known as indoor residual spraying (IRS). With DDT on the walls, mosquitoes are deterred from entering the house.
However, if they do enter they are killed by the insecticides' well-known toxic properties. This form of malaria control eradicated malaria from Europe and North America as well as Taiwan and Mauritius and dramatically reduced malaria in many other parts of the world.
DDT comes out on top
There are various insecticides that can be used in IRS, but DDT comes out on top. Not only is it cheaper than other insecticides, its repellent action is also far stronger.
Millions of people around the globe owe their lives to DDT. But malaria is not just a human tragedy; it is an economic one as well.
In Africa, malaria is the leading cause of death among children and it causes catastrophic harm to the continent's development.
In 2000, Gallup and Sachs estimated that in malarial countries the disease reduces per capita economic growth by 1,3% per year. Thus, controlling malaria not only reduces human suffering, it also allows people to work and sustain themselves and their families, further alleviating human misery.
Vaccines for malaria are being developed, but no effective vaccine exists as of 2005. In 2002 the genome sequence of the deadliest malarial parasite, plasmodium falciparum, was completed, giving rise to a great deal of excitement that this would allow a vaccine to be developed shortly.
If diagnosed early, malaria can currently be treated, but prevention of infection is always much better.
Why isn't DDT being used?
The obvious question is why DDT isn't being used if it is so effective. The short answer is that the controversy and misunderstanding surrounding DDT stops the leading donor countries from supporting its use. One of the biggest concerns surrounding DDT is its possible effect on human health, and more specifically, whether or not it is carcinogenic.
The International Agency for Research on Cancer (IARC), classifies DDT as a possible carcinogen. It should be noted that DDT shares this classification with a number of common household consumables, such as peanut butter, beer and coffee.
Since the 1940s, thousands of tons of DDT have been produced and distributed throughout the world and millions of people have come into direct contact with it in one way or another.
Despite this direct exposure, the scientific world has failed to produce any substantial evidence to back claims that link DDT to health ailments in humans. We do know, however, that wherever DDT has been used in public health, disease and deaths decreased dramatically and human populations began to rise; something one wouldn't expect if DDT was as dangerous as some people make it out to be.
Where did DDT get its dirty name?
The whole matter boiled over in 1962 with the publication of Rachel Carson's blockbuster Silent Spring. Carson's writing raised the dark suspicion that DDT was upsetting the balance of nature. Nowhere did she acknowledge that the chemical had saved millions of lives. Nor did she make it clear how judiciously and selectively the public-health community deployed DDT.
Her criticism was based almost entirely upon the fact that in agriculture DDT was being sprayed indiscriminately. One of DDT's biggest assets, its inability to be broken down quickly, created the suspicion that it adversely affected the environment. It was for this reason that it was named as one of the persistent organic pollutants (or POPs) and included in a list of vilified organic substances known as the dirty dozen.
However, the quantities involved in IRS are minimal: 2 g per square metre. Donald Roberts noted in 1997 that: "treating a 4 square kilometre cotton field – which is the size of a single farm in some locations – takes as much DDT as all the houses in a tropical country the size of Guyana".
Furthermore, the WHO advocates its controlled use for public health and notes, "the improvement in health resulting from malaria campaigns using DDT has broken the vicious circle of poverty and disease resulting in ample economic benefits" such as increased productivity of workers, lower rates of morbidity and the use of previously unoccupied areas that were ravaged by the parasite.
Certain countries now use DDT
While malaria continues to rise around the globe, certain countries such as South Africa, Swaziland, Zambia and Mozambique have seen dramatic declines in malaria cases and deaths.
The one thing these countries have in common is that they have strengthened and expanded their spraying programmes and, with the exception of Mozambique, use DDT.
In fact, in 2000 the South African government lobbied hard at UN Environment Programme meetings for DDT not to be banned by international treaty. The South African government's leadership on this matter has saved countless lives and strengthened malaria control.
Meanwhile, disingenuous and scaremongering anti-DDT campaigns from environmentalist groups has condemned millions of Africans to lives of illness, poverty and early death. – (Jasson Urbach, Free Market Foundation)
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