4 ms·

We all but wiped out bedbugs in the 40's and 50's using DDT. I find the short history of DDT fascinating - in two decades, we eliminated Typhus in Europe, went

by temuze 12y ago

We all but wiped out bedbugs in the 40's and 50's using DDT. I find the short history of DDT fascinating - in two decades, we eliminated Typhus in Europe, went from 2.5 million cases of malaria in Ceylon, Sri Lanka in 1948 to 17 in 1963, we essentially eliminated bed bugs in the US and Canada, wiped most of Dengue fever out out the South Pacific... Then DDT started getting banned after Silent Spring was published and the environmental movement kicked off. Malaria cases went back up to 2.8 million in Sri Lanka in 1969 and a lot of its effects were reversed. It took longer for bed bugs to come back because they don't spread as quickly as their flying counterparts. I'm not a scientist in this field and I don't feel like I can comment on the validity of differing studies about the safety of DDT or its ecological effects. However, I think it's undoubtedly true that in many countries, malaria and dengue and typhus and all sorts of diseases were more of a concern than cancer (and still are). DDT saved millions of lives in the short span of time it was used. To me, this makes the public health questions of the DDT ban incredibly interesting - if you have something that might cause cancer and kill some innocent people but at the same time use it to eliminate disease vectors and probably save more people in the long run, do you keep using it?

nasmorn 12y ago
The Problem is that DDT got mich less effective very quickly due to resistance. Thus the cost/benefit ratio was foreseeably ever worsening. If eridication can not be achieved in under 10 years with DDT it will basically never happen.
- deleted 12y ago
  [deleted]
rm999 12y ago
You make some good points, but you're missing some keys facts about why it was banned and why most people today don't really care that it's banned. This is a good read on the topic: http://www.worldwatch.org/node/517 http://www.worldwatch.org/node/517 tldr: DDT is extremely dangerous because it is fat soluble, which means it accumulates up the food chain. It has been linked to all sorts of potential problems, both ecological and to human-health. The question of malaria is moot, mosquitos quickly developed a resistance to it. You can mitigate malaria with other means, such as bednets. edit: specifically to your point, this is the relevant part (i.e. why it wasn't that controversial): > The campaign managers knew that in mosquitoes, regular exposure to DDT tended to produce widespread resistance in four to seven years. Since it took three years to clear malaria from a human population, that didn't leave a lot of leeway for the eradication effort. As it turned out, the logistics simply couldn't be made to work in large, heavily infested areas with high human populations, poor housing and roads, and generally minimal infrastructure. In 1969, the campaign was abandoned
- temuze 12y ago
  Sure - just like mercury, it accumulates up the chain. Just to be clear, I'm certainly not arguing that DDT is an end-all for all our pest problems. Again, I'm not a scientist. I'm just saying it has an interesting history! Nowadays, I think the modern approach is to treat it as another tool in our toolbox against malaria. This is a good article that discusses that: http://www.washingtonpost.com/wp-dyn/content/article/2005/06/04/AR2005060400130.html http://www.washingtonpost.com/wp-dyn/content/article/2005/06...
- maxerickson 12y ago
  The WHO continues to endorse the use of DDT in malaria control: http://www.who.int/malaria/publications/atoz/who_htm_gmp_2011/en/ http://www.who.int/malaria/publications/atoz/who_htm_gmp_201... 2. Why is DDT still recommended? 2.1 Efficacy and effectiveness of DDT DDT has several characteristics that are of particular relevance in malaria vector control. Among the 12 insecticides currently recommended for this intervention, DDT is the one with the longest residual efficacy when sprayed on walls and ceilings (6–12 months depending on dosage and nature of substrate). In similar conditions, other insecticides have a much shorter residual efficacy (pyrethroids: 3–6 months; organophosphates and carbamates: 2–6 months). Depending on the duration of the transmission season, the use of DDT alternatives might require more than two spray cycles per year, which would be very difficult (if not impossible) to achieve and sustain in most settings. DDT has a spatial repellency and an irritant effect on malaria vectors that strongly limit human-vector contact. Vector mosquitoes that are not directly killed by DDT are repelled and obliged to feed and rest outdoors, which contributes to effective disease-transmission control.
  - rm999 12y ago
    But only for indoor spraying: > WHO recommends DDT only for indoor residual spraying. Countries can use DDT for as long as necessary, in the quantity needed, provided that the guidelines and recommendations of WHO and the Stockholm Convention are all met... The article I linked to discusses indoor spraying and supports it. They argue though that the primary use of DDT in Africa has been agricultural spraying, which is why the resistance formed (and which is what most people oppose).

by temuze 12y ago

nasmorn 12y ago

The Problem is that DDT got mich less effective very quickly due to resistance. Thus the cost/benefit ratio was foreseeably ever worsening. If eridication can not be achieved in under 10 years with DDT it will basically never happen.

deleted 12y ago
[deleted]

rm999 12y ago

You make some good points, but you're missing some keys facts about why it was banned and why most people today don't really care that it's banned. This is a good read on the topic: http://www.worldwatch.org/node/517 http://www.worldwatch.org/node/517 tldr: DDT is extremely dangerous because it is fat soluble, which means it accumulates up the food chain. It has been linked to all sorts of potential problems, both ecological and to human-health. The question of malaria is moot, mosquitos quickly developed a resistance to it. You can mitigate malaria with other means, such as bednets. edit: specifically to your point, this is the relevant part (i.e. why it wasn't that controversial): > The campaign managers knew that in mosquitoes, regular exposure to DDT tended to produce widespread resistance in four to seven years. Since it took three years to clear malaria from a human population, that didn't leave a lot of leeway for the eradication effort. As it turned out, the logistics simply couldn't be made to work in large, heavily infested areas with high human populations, poor housing and roads, and generally minimal infrastructure. In 1969, the campaign was abandoned

temuze 12y ago
Sure - just like mercury, it accumulates up the chain. Just to be clear, I'm certainly not arguing that DDT is an end-all for all our pest problems. Again, I'm not a scientist. I'm just saying it has an interesting history! Nowadays, I think the modern approach is to treat it as another tool in our toolbox against malaria. This is a good article that discusses that: http://www.washingtonpost.com/wp-dyn/content/article/2005/06/04/AR2005060400130.html http://www.washingtonpost.com/wp-dyn/content/article/2005/06...
maxerickson 12y ago
The WHO continues to endorse the use of DDT in malaria control: http://www.who.int/malaria/publications/atoz/who_htm_gmp_2011/en/ http://www.who.int/malaria/publications/atoz/who_htm_gmp_201... 2. Why is DDT still recommended? 2.1 Efficacy and effectiveness of DDT DDT has several characteristics that are of particular relevance in malaria vector control. Among the 12 insecticides currently recommended for this intervention, DDT is the one with the longest residual efficacy when sprayed on walls and ceilings (6–12 months depending on dosage and nature of substrate). In similar conditions, other insecticides have a much shorter residual efficacy (pyrethroids: 3–6 months; organophosphates and carbamates: 2–6 months). Depending on the duration of the transmission season, the use of DDT alternatives might require more than two spray cycles per year, which would be very difficult (if not impossible) to achieve and sustain in most settings. DDT has a spatial repellency and an irritant effect on malaria vectors that strongly limit human-vector contact. Vector mosquitoes that are not directly killed by DDT are repelled and obliged to feed and rest outdoors, which contributes to effective disease-transmission control.
- rm999 12y ago
  But only for indoor spraying: > WHO recommends DDT only for indoor residual spraying. Countries can use DDT for as long as necessary, in the quantity needed, provided that the guidelines and recommendations of WHO and the Stockholm Convention are all met... The article I linked to discusses indoor spraying and supports it. They argue though that the primary use of DDT in Africa has been agricultural spraying, which is why the resistance formed (and which is what most people oppose).