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Thread: Ddt

  1. #1 Ddt 
    Forum Sophomore Hymenophyllum's Avatar
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    Is DDT so bad? I found 2 diferent opinions. One claims that DDT could cure Malaria in Africa (maybe indirectly), but thanks to ecologists it won't. The other says that it is evil. Where is the truth?


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  3. #2  
    Life-Size Nanoputian Flick Montana's Avatar
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    DDT is a shockingly dangerous agent. Here in the United States, one of the biggest side effects from using DDT was the concentration of the chemical throughout the food chain leading to apex predators such as eagles ingesting huge amounts. This caused a deficiency in the formation of their egg shells which resulted in soft shells. By nesting on the eggs, the eagles were destroying them and their numbers dropped off.

    DDT will NOT cure malaria. After a while, mosquitoes even became immune to it so the benefits are NOT long term.

    Not to ignore human impact, neurological disorders have been reported in breast-feeding children in places where DDT is still in use.


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  4. #3  
    Forum Radioactive Isotope cosmictraveler's Avatar
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    DDT has been banned in America so that alone should tell you something.
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  5. #4  
    Forum Professor Zwirko's Avatar
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    This is probably a weird fetish, but I love old photographs from the heyday of DDT and propaganda photos in general.








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  6. #5  
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    The problem with DDT is its indiscriminate use. See Zwirko's photos.

    DDT was the very best insecticide ever for controlling mosquitoes and thereby cutting down the incidence of malaria.

    The operative word being was.

    Mosquitoes are living things with the propensity to overcome obstacles in their environment by evolving. Those that were susceptible to DDT died out, those that were resistant to DDT thrived in their absence. All other insects did the same. By spraying vast quantities all over the landscape willy nilly for not much more than a couple of decades, DDT became ineffective against practically all crop pests. Worst of all, malaria carrying mosquitoes became more and more resistant. We tried to stem the tide by banning DDT for all uses around the world except malaria control, but the damage was done.

    There are a few places where DDT remains effective in controlling mosquitoes/malaria and it is still used there. But now the focus is on bednets to protect people, teaching people to eliminate pools of stagnant water and other targeted strategies against the mosquitoes and against the illness itself. Promising reports of a possible vaccine appear from time to time, but no vaccine has yet appeared.
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  7. #6  
    Forum Radioactive Isotope skeptic's Avatar
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    There is no black and white. DDT was, as Adelady says, a very, very effective insecticide. Statistics show that its disuse was 'coincident' with massive increases in malaria and millions of extra human deaths. The egg shell thing is controversial, and there are some experiments which indicate no effect on egg shell thickness. The biggest thing about DDT is its slow degradation rate, and its bioaccumulation. It has a half life of about 50 years, and it is found in significant (but probably not harmful) amounts in fat layers in Arctic mammals. It is not water soluble, but is fat soluble, so tends to accumulate in fat layers.

    DDT was used in WWII to 'delouse' returning soldiers by spraying them heavily with DDT dust. Follow up studies decades later showed no increase in cancer rates between those soldiers who had the dust versus those who did not. It is probable that a single exposure is insufficient to cause much harm.

    Because of its slow degradation, it should not be used as a broadcast spray in large amounts. However, it is useful in fighting malaria carrying mosquitoes by localised spraying inside the huts of people living in malaria areas. Apparently the malaria mosquito has the habit of stopping frequently. Thus, if it flies into a hut to attack a sleeping person, it will probably land on the walls first, which kills it.

    Resistance is generally a result of under-spraying some areas. Mosquitos in those areas (like the fringe of a sprayed zone) will not all die, and the resistant ones will re-build populations. After a few generations of such selective killing and re-population, all the descendents of survivors will have high levels of resistance. Avoiding such under-spraying largely prevents resistance forming. Which is why a dense spraying of the inside of huts works well.
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