DDT and Malaria

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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 combating 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 analyzing 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 developing alternative technology that could become viable in the future to eliminate Malaria .

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History 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 Use in the United States

After the completion of World War II, DDT became more widely used in the United States, utilized as a pesticide for agricultural purposes as well as commercial ones. Domestic use also became more widespread. The high demand of DDT caused the United States to use approximately 1,350,000,000 pounds of the chemical during a thirty year period (Environmental Protection Agency, 2007).

It was not until 1960 that DDT use began to decline due to the development of alternative pesticides and growing insect resistance. Health concerns were also beginning to become more publicized during this time due to Rachel Carson’s book, Silent Spring. Because of these changes and concerns, DDT use in agriculture diminished to such as degree that by the 1970s the only crops that were still be sprayed were cotton, soybeans, and peanuts (Environmental Protection Agency, 2007).

December of 1972 saw the United States Environmental Protection Agency ban all use of DDT. Although the actual decree was presented much earlier that year, sufficient time was needed to switch over to purchasing alternative pesticides. The ban was put in place because of greater recognition of the threat DDT posed to both human and animal health (Environmental Protection Agency, 2007).

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 Bate 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.

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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 Bate 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

General Characteristics of DDT

DDT is a persistent pollutant which means that it is resistant to environment degradation. DDT can remain in the environment and biological life forms such as humans and animals for up to 30 years. DDT, DDD, and DDE stick strongly to soil and can remain in soil for hundreds of years (Weis & Cutler).

DDT Effects on the Environment

In 1962 Rachel Carson, an American Marine Biologist, published a book called Silent Spring. She was the first scientist to discuss the environmental impacts of spraying DDT. Carson mentioned that apex predators which have a crucial role in maintaining the health of the ecosystem, on average have the largest concentration of DDT than other animals. Carson thought that the consumption of DDT in animals was threatening to the environment because DDT may cause a decline in certain animal species. Carson claimed that DDT was responsible for the decline of bird species such as the falcon and brown pelican. Most of the accusation made by Carson about the negative environmental impacts of DDT were groundless and unscientific (Bate & Tren, 45). Although, most scientific evidence was half-baked many countries including the US in 1972 banned DDT use anyhow (Bate& Tren, 47).

In 1964 South Africa banned DDT use. In 1969, they had a large increase in malaria infection from 17 to 500,000 (Bate & Tren, 46). In 1974, South Africa banned DDT only for agricultural use because they realized after the dramatic increase of malaria they needed DDT to bring it under control (Bate & Tren, 46).

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The Environmental Debate over DDT

Environmentalists argue that spraying DDT in South Africa will allow mosquitoes to become resistant. On the other hand, scientists argue that even if mosquitoes became resistant to DDT, it would not significantly increase malaria rates (Bate & Tren, 47).

Environmentalists also argue that DDT is not sustainable for the environment because it threatens a decline in natural capital such as forest and wildlife that cannot be substituted (Bate & Tren, 48). On the other hand, scientist argue that the way DDT is used for malaria control does not affect the outside environment. For instance, in South Africa use of DDT is managed and controlled by only spraying the pesticide inside houses (Bate & Tren, 59). This method allows only a small affect on the environment.

There is no significant evidence that confirm environmentalist claims about the harm DDT have on the environment. Even though this fact is widespread, environmentalist organizations such as Greenpeace do not take that fact into account. Greenpeace states: “…relying on precautionary approach based purely on science is not good enough” (Greenpeace, 2000). Some researches feel that environmentalist such as Greenpeace forget that DDT saves millions of lives every year (Bate & Tren, 59).

The Effects of DDT on Human Health

General DDT impacts on Human Health

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DDT is a persistent, toxic chemical; it easily collects in the food chain posing a proven hazard to non-target organisms such as fish and wildlife and otherwise upsetting the natural ecological balance (EPA). When DDT is in use such as for agricultural use, DDT would drain into streams; then DDT would flow into river, ponds, and lakes where people fish live. The fish are affected by DDT. Humans eat those fish, which also placed DDT into our systems (Urquilla). Over time it had been getting stored to points where it could harm the born and unborn. DDT has eight years of the half-life. If a body keeps consuming this pesticide it will get cancer and usually die. DDT gets into our bodies and it stays there, usually in thyroid, testes, fatty organs, and adrenals. DDT also stayed in tinier concentrations in our livers and kidneys. It tends to stay in the fat bodies of our bodies. DDT has very high concentrations in human milk (Urquilla). Depending on how much we weigh, we can measure the amount of DDT that our body tolerate. You will die at concentration above 236mg DDT per kg of body weight. Concentration of 6-10 mg/kg leads to such symptoms as headache, nausea, vomiting, confusion, and tremors. Currently there are some debates as to whether DDT can increase a woman’s chance of breast cancer (Szaflarski).


Problems of formula feeding In Africa

DDT can interfere with the feedback loop in the pituitary gland, which releases the milk producing hormone prolactin. Exposure to DDT at critical points in pregnancy or just after childbirth can reduce the output of breast milk, or even dry it up. In such instances the mother will turn to formula, which is expensive. And in Africa formula feeding often leads to another death sentence for babies: diarrhea (infants have no immunity to the microbes that abound in contaminated drinking water throughout much of the continent). Then, exposure to DDT may cause as swift and bleak an outcome as exposure to a mosquito (Larsen).

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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 combating 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 combatant (Liroff). It has been formulated that USAID has saved over 10 million lives by funding the use of DDT (Bate & Tren).

Economic Costs of Malaria

Malaria's negative effect on South Africa can be evaluated at various sectors throughout the economy. The costs of malaria include, health-care costs; medication, testing, and physician time, vector control costs, malaria control programme costs, mortality costs, a decline in tourism, and most importantly production costs. Malaria reduces the labor force, which in turn reduces productivity, causing output to decrease. A production decrease effects the African economy and more directly, its inhabitants (Bate & Tren).


		             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

Although there is a great deal of controversy concerning the use of DDT, the benefits of DDT usage in the context of South Africa, far outweighs its costs. DDT house spraying is inexpensive and highly effective. DDT usage only requires a minimal amount to be sprayed within the home by trained sprayers. The alternatives to DDT are impractical in South Africa, either being too expensive or insufficient in combating malaria. For example, bed nets can only protect 1-2 people at a time. Whereas it has been proved that the normal amount of DDT used on a cotton field is able to protect all the high risk residents of a small country from malaria (Attaran & Maharaj). By decreasing the number of malaria cases that either causes temporary unemployment or death, will have a positive effect on South Africa's economy, boosting its level of output.

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 recognizes 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 (Brown).

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Alternatives to DDT

Although DDT is the most effective and least expensive method in combating Malaria, it has been proven to have adverse effects on the environment and human health. Certain species of mosquitoes have also evolved to be resistant to DDT, making it ineffective. In the future it would be beneficial for South Africa to discontinue use, but first there must be an adequate alternative that meets both the effectiveness and inexpensiveness of the current practice of spraying DDT. Many alternatives have been found to be successful in combating malaria, like in Mexico. However the countries that rely on DDT are some of the poorest in the world and would need both technical and financial support from other countries to develop an alternative. There has already been some research on transgenic mosquitoes that are equipped to be immune to being carriers for malaria and the dengue fever. However this research is still in the early stages and problems are predicted to occur when it comes time to introduce these engineered mosquitoes into the wild. The engineered mosquitoes are likely to have trouble competing and thus will have a lower survival rate. Questions also arise about the manufacturing process itself as far as it would be very unlikely to have engineered an immunity to a diseases without altering something else (Levy). Right now DDT still proves to be the best combatant to malaria in South Africa, but funds should be geared toward finding a future alternative.

References

1. Attaran, Amir, and Rajendra Maharaj. "DDT for Malaria Control should not be banned." British Medical Journal 321 (2000).

2. Brown, David. "WHO Urges Use of DDT in Africa." Washington Post 16 Sept. 2006: A9.

3. Carson, Rachel. Silent Spring. New York: Houston Mifflin Company, 2002

4. DDT Regulatory History: A Brief Survey (to 1975). History. 2007. U.S. Environmental Protection Agency. <http://www.epa.gov/history/topics/ddt/02.htm>.

5. Department of Environmental Protection. “DDT—A Brief History and Status.” Washington D.C. 2007. www.epa.gov/pesticides/factsheets/chemicals/ddt-brief-history-status.htm.

6. Larsen, Kim. “Bad Blood.” On Earth. December, 2007: 3. http://www.onearth.org/article/bad-blood?page=3.

7. Levy, Sharon. "Mosquito Modifications: New Approaches to Controlling Malaria." BioScience 57 (2007): 816-21.

8. Liroff, Richard. "Commentary: Reduction and elimination of DDT should proceed slowly."British Medical Journal 321 (2000).

9. McGinn, Roberts, and Trankina are all from the same book entitled “Taking Sides: Clashing Views on Environmental Issues” Twelfth Edition Ed. Thomas A. Easton. McGraw-Hill Contemporary Learning Studies, 2008.

10. Metcalf, R.L., Insect Resistance to Insecticides, Pesticide Science, 1989, 26: 333-358.

11. Pesticides News No.40, June 1998, p18-20 http://www.pan-uk.org/pestnews/Actives/ddt.html.

12. Silberner, Joanne. “WHO Backs Use of DDT Against Malaria.” NPR, 13 November 2008. www.npr.org.

13. Szaflarski, Diane. “Effects of DDT.” Cruising Chemistry. http://www.chem.duke.edu/~jds/cruise_chem/pest/effects.html.

14. Tren, Richard, and Roger Bate. “Malaria and the DDT Story.” The Institute of Economic Affairs, London: 2001.

15. Tren, Richard. "The Economic Costs of Malaria in South Africa." http://www.malaria.org/tren.html.

16. United States Environmental Protection Agency. “DDT Regulatory History: A Brief Survey (to 1975).” 12 November 2008. http://www.epa.gov/history/topics/ddt/02.htm.

17. Urquilla, Janelle. “Before and After DDT.” DMJT’s View on DDT. http://warrensburg.k12.mo.us/ew/ddt/tracy.html.

18. Urquilla, Janelle. “DDT’s Effects on the Earth and Humans.” DMJT’s View on DDT. < http://warrensburg.k12.mo.us/ew/ddt/janelle.html>.