Much-maligned DDT has key role in battling malaria

Jasson Urbach | 10 Jul 2006
Cape Times

In the time that it takes you to read this sentence, at least one child has died and many more will have suffered needlessly from a disease that is entirely preventable and curable.

Malaria is responsible for the death of approximately one million African children every year and as many as three million people worldwide. Malaria is not only a human tragedy; it is an economic one as well.

In 2000, Sachs and Gallup estimated that in malarial countries the disease reduces per capita economic growth by 1.3% per year.

This equates to approximately $12 billion in forgone income.

Therefore, controlling malaria will not only reduce human suffering, but it will also allow people to work and sustain themselves and their families, which will help to alleviate human misery and poverty.

As has been widely reported and commented upon, one of the best ways to control malaria and reduce the burden is to stop the deadly anopheles mosquitoes from biting humans. One of the most effective ways of doing that is to spray tiny quantities of the insecticide environmentalists love to hate, dichloro-diphenyl-trichloroethane (DDT), on the inside walls of houses in a process known as indoor residual spraying (IRS). DDT lasts for up to a year and primarily repels mosquitoes so that they won't even enter a sprayed house.

However, should they enter, it will kill the cunning beasts and protect the residents.

Despite its remarkable life-saving properties, DDT has a bad name, which it gets mostly from Rachel Carson's 1962 blockbuster book Silent Spring. Her writing raised the dark suspicion that DDT was upsetting the balance of nature. She was entirely dismissive of the fact that the chemical had saved millions of lives and continued to do so. Nor did she make it clear how judiciously and selectively the public-health community deployed DDT.

Carson's 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 (POPs) and included in a list of organic substances known as the dirty dozen. The International Agency for Research on Cancer classifies DDT as a possible carcinogen.

It should be noted that while this statement may not be definitive by any means, DDT shares the 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 out.

The World Health Organisation advocates the controlled use of DDT 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.

Many African countries are beginning to introduce the targeted use of DDT for indoor residual spraying. South Africa has played a leading role in malaria control in Africa, in large part because of its success in dramatically reducing malaria cases and deaths by

reintroducing DDT after a severe epidemic in the 1990s.

After DDT was brought back in 2000, malaria cases fell by around 80%.

The South African government's leadership on this matter has saved countless lives and strengthened malaria control. Recently, a number of other African countries have begun to weigh the substantial cost in human lives against the unfounded hypothetical risks of DDT.

The health ministers of Tanzania, Uganda and Mozambique have announced their intentions to use DDT in malaria control. The United States Agency for International Development (USAid) also recently announced that it would endorse the use of DDT for indoor residual spraying.

Various insecticides can be used in IRS, but 60 years of use confirm DDT comes out on top. Not only is it cheaper than other insecticides, but it lasts longer. It also acts differently; primarily as a repellent in stopping mosquitoes from ever entering houses, which is a major benefit.

Support for the use of DDT in combating malaria-carrying mosquitoes is growing, and an increasing number of government agencies are adopting new and effective combination drugs for avoidance and treatment of the disease, which augurs well for malaria control. Now we have to ensure that changes in policy result in saved lives.

Urbach is a director of the health advocacy group Africa Fighting Malaria and a Fellow at the Free Market Foundation. This article was first published on the foundation's website (