Since Rachel Carson’s book, Silent Spring, launched the chemical DDT to infamy, the powerful pesticide has been the subject of controversy. Responsible for the devastating environmental and health impacts that have won the chemical its bad name, DDT’s potency as an insecticide also won it a Nobel Prize and the support of many health activists fighting malaria. The use of DDT for malaria has many pros and cons that cause environmentalists, health organizations, and governments to fall on either side of the fence. The main questions to ask in this nuanced argument is whether the long-term health and ecological impacts of DDT outweigh the health benefits of DDT for malaria, and whether there are alternatives that might work better at lower cost.
DDT, an abbreviation for dichlorodiphenyltrichloroethane, is an insecticide that kills insects by disrupting their nervous systems, causing convulsions and death. Malaria is a potentially deadly disease caused by a parasite that lives on certain types of mosquitoes. Because the parasite itself is so hard to kill in great numbers, focus has generally been set on killing the carrier. Since World War II, people have been using DDT for malaria, as well as in agriculture, with great success. There are, however, some big problems with DDT.
DDT was banned, first in the United States and then worldwide, for its harmful effects on health and the environment. As a persistent organic pollutant, DDT stays in the environment, especially in the soil, for a long time and doesn’t dissolve in water. As it accumulates and animals become exposed, health impacts begin to appear in fish, other marine animals, birds, and even mammals, such as humans. In birds, DDT has shown to cause shell-thinning in eggs and is thought to be partially responsible for the near extinction of the bald eagle. In humans, there is evidence that DDT causes deterioration of genetic integrity, cancer, difficulty breastfeeding, early miscarriage, and lower semen quality, amongst other negative health impacts.
There are also compelling reasons why we should use DDT for malaria, however, and the World Health Organization (WHO) has supported limited use of DDT for such health purposes. Malaria is most common in poorer nations, especially in sub-Saharan Africa, so DDT is an attractive choice as a relatively inexpensive insecticide. The climates in these regions also lend themselves to faster degradation of the chemical, reducing its persistence. When so many people are dying of malaria, many DDT supporters cannot see any justification for not fighting the disease with whatever tools available.
Many DDT critics, such as Rachel Carson, support cautious, limited use of DDT for malaria. Still, even the restricted use of DDT in malaria stricken regions has led to serious health issues, negative environmental impacts, and a very dangerous rise in DDT resistant mosquitoes. Some proponents argue that the limitations on DDT should be lifted for a more effective fight against malaria. Others say that this would just increase the aforementioned problems and would not eradicate the disease, especially in places where the climate allows mosquitoes to survive year-round. Alternative pesticides, physical barriers to mosquitoes, and drugs to prevent and treat malaria are also available as substitutes or tools to use in tandem with DDT for malaria.