DDT and Malaria

Abstract

Dichloro-Diphenyl-Trichloroethane, commonly known as DDT, is a pesticide that has been banned in the United States, Europe, and many other countries. Currently it is used for an emergency basis in many developing countries, such as Africa and South America, for combatting Malaria. We will be focusing on Sub-saharan Africa and their uses of pesticides, specifically DDT, to battle Malaria. We understand the externality costs on the health of humans and wildlife, but in these extenuating circumstances we support the use of DDT as a lesser of two evils. By analyizing the costs and benefits of using DDT in these third world countries, we have found that the use of DDT has lower monetary costs. The risk of humans contracting Malaria, has higher economic costs that hinder the development of the country. It is common in Sub-Saharan African countries, for the citizens to be more concerned with their conditions rather than factors that could effect their health later in life. However, we hope to also stress the necessity of devloping alternative technology that could become viable in the future to eliminate Malaria .

Histroy and Usage of DDT

Dichloro-diphenyl-trichloroethane, commonly known as DDT, was first created in 1874. It was not until 1939 however, that it was found to be quite proficient at killing pests and began to be widely used as a pesticide in the United States.

DDT and Malaria Control in Sub-Saharan Africa

DDT was first used on the continent of Africa in South Africa in 1946. Here it proved successful in eradicating the Malaria vector mosquitoes, greatly decreasing their numbers and the amount of outbreaks. The number of Malaria cases was reduced by one tenth shortly after its use in the region (Tren and Bates 2001). In 1956 reports of DDT resistant mosquitoes were coming out of northern Nigeria with other cases in the Middle East and Indonesia. Since this time, even more species of mosquito have become immune to DDT’s effects, yet not so many to render the chemical nonviable (Silberner 2008). DDT was used continually in many African countries until the late 1970’s.

The Decline of DDT and Current Usage

In 1972 the United States banned DDT with many other countries following suite. Despite the ban, the U.S. still continued to export approximately 35 million pounds of DDT to developing countries for Malaria control (United States EPA 2008). Today although a Northern Province in South Africa still routinely sprays DDT for Malaria, currently many African countries only used DDT on an emergency medical basis (Tren and Bates 2001). This has begun to change however, as the World Health Organization recently endorsed the use of DDT to fight Malaria, suggesting that African households be sprayed twice a year (Silberner 2008). Countries such as Tanzania, Uganda, and Zambia have recently lifted bans that previously prevented them from utilizing DDT against Malaria. These trends suggest that DDT will become more widely used on the African continent in the near future.

The Effects of DDT on the Environment

Persistent

DDT is a persistent organic pollutant which is an organic compound that is resistant to environmental degradation. DDT can remain in the environment and the biological life forms within the environment up approximately 30 years.

Bioaccumulation and Biomagnification

DDT bioaccumulates in fat; it is not a water-soluble chemical. Bioaccumulation is dangerous in that species at the top of the food chain receive a much higher dose of DDT than lower-tiered species. Small animals will only ingest small amounts of DDT; however, this process magnifies as predator/dominating species ingest many small animals. (See diagram) Human breast milk?

Vector Resistance

Increases insect resistance- “By 1984 a world survey showed that 233 species, mostly insects, were resistant to DDT” (Metcalf). We need to search for an alternative just in case the mosquitoes that carry malaria start becoming resistant to DDT. “Today, DDT resistance is widespread in Anopheles” (McGinn 285).

Animal Populations

-Causes catastrophic effects in predatory bird populations during reproduction- “DDT and its metabolites can lower the reproductive rate of birds by causing eggshell thinning which leads to egg breakage, causing embryo deaths… Predatory birds are the most sensitive. In the US, the bald eagle nearly became extinct because of environmental exposure to DDT” (Pesticide News). -Causes hermaphroditic and feminizing effects in fish (Trankina 305).

An Economic Analysis of DDT

Malaria affects over 3 million people a year and over 1 million die every year. Most of theses deaths are children under the age of five. Current malaria control methods include bed nets, cleaning mosquito breeding areas near villages, delivering anti-malaria drugs, and the spraying of DDT indoors. DDT is currently the most effective and efficient method for combatting malaria. However, the use of DDT has raised controversy over its adverse affects on human health and the environment.

Use in Africa for Malaria Control

Countries around the world, including the United States, have banned the use of DDT. Only two countries produce DDT, China and India, while more than two dozen countries still use DDT today as an anti-malaria vector.

Economic Costs of Malaria

Health-care costs: medication, testing, and physician time

Vector control costs

Malaria control programme costs

Hindrance to tourism

Mortality costs

Productivity costs

		             Cost (in Rand)	% of Total
Indirect Costs	
        Productivity Costs	5,082,550	41
			
Direct Costs	
        Malaria Tests	         595,167	5
	Evacuation Costs	 2,794,000	22
	Drug Costs	         640,349	5
	Physician/Nurse Time     2,122,577	17
	Hospital Costs	         1,197,737	10 

• Rand is the currency of South Africa. 1 Rand is approximately .0975 USD or similarly 1 USD is approximately 10.25 Rand.

Benefits of DDT usage

DDT house spraying: Inexpensive Highly effective Trained sprayers apply a minimal amount of DDT

Normal amount of DDT used on a cotton field, can protect all high risk residents of a small country from malaria

Bed nets can only protect 1-2 people

USAID has saved over 10 million lives through the funding of DDT use.

Over 1 million people die from malaria every year, most are children under the age of 5

WHO's support for DDT use in Africa

On September 25, 2006 the World Health Organization reversed its 30 year policy and declared its support for the use of DDT indoors in South Africa. In previous years the WHO had been against the use of DDT because of its harmful side effects on the environment and the health of human beings. However, in the context of South Africa, the WHO believes the benefits far outweigh the costs. A physician at the Environment Health Department stated that, “DDT is not the single answer, but it can be a part of the solution until we find a better alternative”(Brown). Although the World Health Organization recoginizes the potential dangers of DDT use, it understands that in South Africa, where malaria impacts the daily lives of its citizens, DDT use is the most effective way to control the spread of Malaria.

Alternative Malaria Controls

• Many alternatives have been found to be successful in combating malaria, like in Mexico • However the countries relying on DDT are some of the poorest in the world o Need technical and financial assistance from developed world • India and China are the only countries who product DDT o Levy, Sharon. "Mosquito Modifications: New Approaches to Controlling Malaria." BioScience 57 (2007): 816-21. o DDT accelerated the evolution of insect resistance (817) o Build a better mosquito, immune to being a carrier for malaria o Transgenic mosquitoes have been built to be immune to malaria and dengue fever  Problem is transferring this mosquito into the wild  Likely to have trouble competing, survival rate lower  Unlikely to have engineered an immunity to a diseases w/o altering something else

Conclusion

Right not DDT is the most effective solution for controlling the spread of malaria, however funds should be geared towards finding an alternative method of combating malaria

References

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