What is DDT?
How was it found?
DDT was originally seen as the ideal pesticide. It was a cost efficient chemical that initially had an impressively high toxicity to insects, with no acute toxicity to humans. Its extremely negative effect on insects proved DDT to be an effective way to exterminate insects that kill agricultural crops, as well as control insect-transmitted diseases.
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During World War II, when a budding epidemic of typhus in Naples, Italy started to spread, civilians and troops were sprayed with DDT. The epidemic was stopped in its tracks.
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DDT was discovered to be an insecticide in 1939 by Paul Muller. He was a scientist working for Geigy, a Swiss firm that was focused on the chemical development of agricultural insecticides. Products with DDT entered the Swiss market in 1941. Seven years later, in 1948, Muller received the Nobel Prize for medicine and physiology in recognition for the lives DDT saved.
After its commanding cameo in World War II, DDT was widely used for public health purposes as a pest control in hot climates; this includes the maintanence of malaria and typhus, since both are diseases spread by mosquitoes. DDT also gathered popularity in developed nations as an effective agricultural insecticide. It was used extensively on fruit trees and vegetation crops, as well as in cotton fields.
What is it used for?
As DDT use continued, insect populations began to develop a resistance to it. To combat this unexpected persistence, the amount of the pesticide used on crops was significantly increased. The greater the amounts of DDT applied to crops, the more the insects became resistant.
Concern within the scientific community about the potential of side-effects associated with DDT began to fester. In 1962, Rachel Carson brought these concerns to the general public through her book Silent Spring. The book exposed potential environmental problems associated with DDT use. The book's disturbing claims that DDT was respondible for the population drop in birds of prey as well as for the rising cancer cases in humans immediately caught public attention.
The concern became politicized. Various hearings within the United States regarding the use of DDT and its consequences were brought. In 1972, the United States Envrionmental Protection Agency banned all the uses of DDT except those that were essential to human health. Three years prior to that, Sweden had banned the use of DDT for agricultural purposes. Many other developed nations followed suit.
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DDT is one of the only inexpensive and highly effective approaches available to fight against the transmission of Malaria through mosquitos, which inflicts over 300 million people and takes the lives of over one million every year. Malaria typically affects economically immature countries throughout the tropics, making DDT a viable life-saving solution to this plague.
A campaign to wipe out malaria proved in the end that DDT reduces cases and transmission of malaria significantly. In the 1950s and 1960s, DDT spraying decreased Sri Lanka’s malaria epidemic from 2.8 million cases and 7300 deaths to a mere 17 cases and no deaths per year. Other areas throughout the world, such as India and South America, were able to completely eradicate the disease.
Why does DDT have a bad reputation?
Where is DDT found in our current environment? How are we exposed?
It takes approximately 15 years for DDT to dissociate and disappear from the environment. Even though the use of DDT was banned in 1972, there still potential for leftovers in our environment.
DDT can be found in the soil. Growing plants and local animals can absorb the DDT from contaminated soil. People who eat these plants or animal can potentially ingest some DDT. Also, this contaminated soil can runoff into water supplies and other populated areas.
DDT can be found in water. The fish and shellfish in contaminated water absorb the DDT. Humans who eat this aquatic life have potential to ingest DDT.
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DDT can be found in the atmosphere. Countries that continue to use DDT have no way of containing their contaminated air. Wind currents can carry DDT to populated areas where humans have the potential to ingest it.
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Humans can be involuntarily exposed to DDT if it is improperly used or disposed of. As well, if products that were grown on farms that permit the use of DDT are consumed, then the person consuming might ingest the chemical.
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Source: Wikipedia online: http://en.wikipedia.org/wiki/DDT.
