Slashdot Mirror
DDT or Malaria -- Which is Worse?
Assassin bug wonders: "Although the topic of malaria has been discussed on Slashdot, DDT use has not. After having banned DDT (C14H9Cl5)" in 2004, Tanzania has reversed their ban on DDT use. What is the Slashdot community's opinion regarding the use of DDT for mosquito control versus genetically modified mosquitoes?"
"Key facts to consider:
- Insects have developed resistance, for every tactic that has been used against them (including biological control, crop rotation, and various chemicals)
- Although the direct effects of DDT on humans might be benign, the effects on wildlife and the environment are well documented
- In some countries, such as India, popluations of DDT-resistant mosquitoes exist
- The fitness (i.e., reproductive success in the wild) of mutant mosquitoes is not well understood."
The World Wide Web is dying. Soon, we shall have only the Internet.
The DDT necessary to save thousands of lives in the world's malarial hellholes is miniscule compared to that required for the crops of even a medium farm.
And DDT-hate on the part of international aid organizations (international aid is the entire health budget for some impoverished African countries) has led to countries refraining from using DDT.
Not using DDT kills poor Africans.
DDT is the cheapest, most effective way of protecting against the world's deadliest disease. Anti-malarial netting is somewhat effective, but simply does not compare to DDT.
"It is more sensible in some cases to take a small amount of damage in preference to having none for a time but paying for it in the long run by losing the very means of fighting [is the advice given in Holland by Dr Briejer in his capacity as director of the Plant Protection Service]. Practical advice should be "Spray as little as you possibly can" rather than "Spray to the limit of your capacity.""
-Rachel Carson, Silent Spring
Note the last sentence. It seems she KNEW that in some cases, not using DDT would amount in a LARGE amount of damage, and in these cases, using DDT would be unavoidable. Spray as little as you possible can seems to be common sense, but may not be to the uneducated.
It IS known that DDT builds up in the tissues of organisms high up in food chains. Perhaps studies don't indicate that DDT directly causes any sort of harm, but I don't think having an organochlorine in ANY fleshy parts is a good thing.
No, Mr. Green. Communism is just a red herring.
The problem with pesticides and antibiotics is that they are often abused and misapplied through ignorance, stupidity and greed. Read how China may have fscked the entire world by using a human antiviral drug in an effort to protect the Chinese poultry industry from bird flu.
Mea navis aericumbens anguillis abundat
but chemical manufacturing companies largely stopped making it after it got a bad name from the environmental concerns.
You mean like after it decimated the ecosystem on Borneo, forcing 14,000 cats to be parachuted in to stop the population from dying of bubonic plague and typhus.
Alleged? Alleged? C'mon. This is well documented. DDT doesn't kill humans, but it sure does screw with a lot of other animals. It can be used intelligently, but it can also be used stupidly, too.
It's not even clear that when it's used intelligently that it's cost effective to do so. USAID doesn't believe that it is.
Found your comment interesting, so I googled it and found this very interesting. Thought others might find it a good summary.
Click on the top link about borneo on this Harvard Page
This is known in reasoning circles as a "false dilemma".
DDT is very cheap and effective in the spot you're applying it to. And therein lies the problem: it's almost too good. The step from using it where it is effective and safe to using where it has unwanted side effects has historically proven to be very short.
Lacking DDT, the industry has had to develop alternative approaches, such as IPM, which are more information and biology centric, and new materials which are more narrowly targetted and which break down in the environment in a more benign way. This requires more up front effort and investment, but in the end is probably more effective.
Consider one common traditional use of DDT: Fogging to kill adult mosquito populations. The mosquito has to encounter the DDT on the wing or land in a place where there was residual toxic effect. Since the mosquito could be literally anywhere, this means you must saturate an entire area surrounding human habitations by fogging it. In the old days, you waited for a nuisance problem or a disease outbreak, and then fogged everything you could reach and hoped you were in time to stop human transmission. I've talked to public health researchers who believe that most such efforts tend to be undertaken after the actual problem has past. Or if you were proctive, you might try to treat preventatively, killing not only mosquitoes (you never get them all), but beneficial insects as well.
Today, if you can manage it, you find the aquatic habitat in which mosquito larvae hatch and develop, and if you can't drain it (e.g. artificial containers like abandoned machinery), you treat it with a narrowly targeted larvicidal material. BTI and Baccillus sphaericus for example, are endotoxic crystals that only act in aquatic larvae with high pH guts -- midges and mosquitoes mainly. If the mosquitoes have pupated, you treat with a material which forms a film on the water, blocking their breathing tubes; in the old days we used diesel oil, now we have specially formulated oils and even alcohols that form monomolecular films.
However, this involves knowing where the habitat is, which is information-centric problem. You need trained inspectors in the field who know what to look for and what to use. Even fogging operations are much more sophisticated; you don't just spray and pray. You have a trapping program to monitor adult populations so you don't end up fogging the wrong places. The technology involved for trapping is mostly rudimentary , but you need trained users who can sort and identify mosquitoes by species. Not all mosquitoes bite people or carry disease after all. Furthermore you'd be surprised how many untrained people mistake other insects such as crane flies for mosquitoes.
But it remains thrue, for the developed world Information + Biological Knowledge + Specific action pesticides = Control with fewer side effects.
With respect to human and animal health, there is little threat to human health from direct exposure to DDT in the concenrations that are effective. The established problem with DDT is bioaccumulation: the concentrations of DDT and chemical products of DDT break down are amplified as they go up the food chain. In certain key applications, such as house interior treatments, this is not a concern however, so it should be possible to use DDT this way.
In places like Africa, DDT used in domestic treatments would be a tremendous boon. The forms of Malaria that infect humans, unlike many other mosquito borne diseases such as the various encephalitis agents, don't have a natural animal reservoir. It spreads from person to person. Personally, I can imagine Malaria being eradicated, like smallpox, and domestic DDT treatments could play a part in this, if its use could be monitored and controlled.
I've been involved with equipping teams to go to Africa for malaria surveillance and for house treatments. One of the problems you face is that in many poor areas, theft is rife. I've had guys tell me they have
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