September 18, 2006
From the desk of Jane Galt:Perish the pushers
In The Science and Politics of DDT, John Quiggin writes:
And the substantive change in WHO guidance is much less dramatic than the rhetoric would suggest. WHO is now recommending the use of indoor residual spraying (IRS) not only in epidemic areas [as in the past] but also in areas with constant and high malaria transmission, including throughout Africa.
It’s far from clear that the change is backed up by a scientific analysis of the relative cost-effectiveness of the options. But, as with all the fads and fashions in areas like this, cost-effectiveness is not necessarily the most relevant criterion. The US appears willing to put in a substantial amount of extra money, and the US wants to push DDT. So, it’s probably better to please the donors, than make a stand on the science and risk losing the money.
No companies in the US currently manufacture DDT, and given its age, any patents must have expired long ago. The implication seems to be that we're pushing DDT just for the hell of it. I also infer that the US role as pesticide-pusher must be relatively recent, since the WHO was apparently not previously afraid of pissing us off. Can any of my readers comment?
Instapundit's blog post: http://instapundit.com/archives/032591.php
Posted by: Kevin P. on September 18, 2006 12:22 PMJohn Quiggin:
So, it’s probably better to please the donors, than make a stand on the science and risk losing the money.
The same can be said for research finding an anthropogenic cause for global warming.
Posted by: Kevin P. on September 18, 2006 12:32 PMWhat? Someone making statements about DDT out of ignorance? Say it is not so! (Kind a reminds me of how the reviews for the The Politically Incorrect Guide to Science had people saying both "Oh, come on, hormesis [the theory of harmful materials being beneficial in small doses] is such a crank theory. You're not being oppressed, it's just wrong." AND "Uh, hormesis is already well-accepted ... quit complaining.")
Btw, just a heads up: even Ralph Nader supports some level of re-introduction of DDT.
Posted by: Person on September 18, 2006 12:33 PMIt's being pushed for political reasons -- the agricultural use of DDT was banned for enviromental reasons and this is a way to make a blood libel on environmentalists, by blaming them for every case of malaria since 1972.
Posted by: Tim Lambert on September 18, 2006 1:08 PMWell, I guess Tim thinks saving lives is a petty "political" reason. I wonder if he's willing to allow deaths to continue as a preferable alternative to being proven wrong...
Posted by: Person on September 18, 2006 1:13 PMReason magazine has a story on this here. Anyone looking on more background on this issue ought to follow the links in the post.
By the way, I can't seem to find a way to link to the post without it starting at the comments section of the blog. You need to scroll up to see the actual post.
Posted by: happyjuggler0 on September 18, 2006 1:16 PMRead the comments section in this post. http://www.gnxp.com/blog/2006/04/ddt-myths.php
I'll take Cochran's view of the situation over Lambert's any day.
China still produces plenty of DDT (4,000 tons a year, according to China Daily from 2004). Officially, it's not used as a pesticide, but of course that 'officially'. When I lived in Hong Kong in the 1990s, periodically we'd hear on the news about a family that ended up in the hospital from eating vegetables (if you ever go to China, don't eat salads!). Farmers on the mainland either couldn't read the label or reasoned that "if a little is good..." Of course it wasn't always DDT - sometimes it was lindane or something else.
Researchers at HK Baptist University have found DDT in the breast milk of Hong Kong mothers, since most food in HK comes from the mainland. Luckily the US doesn't get many vegetables (or fish?) from China, but anyone who drinks green tea is probably picking up traces of DDT periodically.
People that are worried about the environmental effects should focus first on the use of DDT in pesticides. It appears to be pretty safe when properly used indoors to control mosquitos. But I suppose one could argue that, as long as it's produced and distributed, it may be hard to control how it's used.
Posted by: Ann on September 18, 2006 1:20 PMIt's cheap to make.
It kills all the insects and leaves the vegitibles.
It is easy to disperse.
It is like a Neutron Bomb for bugs. Why oh why, did they stop using DDT? There are alot of plusses. What were the minuses?
Posted by: Paul on September 18, 2006 1:21 PMTim Lambert:
...and this is a way to make a blood libel on environmentalists, by blaming them for every case of malaria since 1972.
Naturally, Tim Lambert's opponents can only have the basest motives. It is simply not possible that anti-malarial DDT proponents may believe that their science is better. Or God, forbid, that they might actually be right and it might be that environmentalists might have overreacted (not that this would ever happen).
No, those could not be the reasons. The blood libel is the only possible motive.
(We should be thankful that Tim has not yet realized that the DDT proponents really secretly want to destroy the environment and all living things in nature).
Posted by: Kevin P. on September 18, 2006 1:43 PMI was under the impression that the US was one of the strongest forces behind the global banning of DDT use. Do we now support lifting that ban? Am I mistaken here? If not, when did the policy change, and why?
Paul: From what I've read, it doesn't break down in nature, and in certain food chains, large amounds of the pesticide can build up in certain predatory species. Birds of prey were especially susceptible to DDT buildup, and it caused thinner eggshells and fewer eagles.
Posted by: Daniel Chapman on September 18, 2006 1:50 PMYou don't have to go to Africa to feel the impact of excessive fear of pesticides.
When West Nile first appeard in the NYC area, Rudy Guiliani lead a campaign to blast every mosquito in the area (as did New Jersey). But in Connecticut the stamford gold coast balked at using relatively benign (non DDT) pesticides.
I am firmly convinced that an all out effort in the NY/NJ/CT area could have kept West Nile Virus out of the US. Now we have another endemic virus that kills at least 20-50 per year, sickens thousands of others as well as a very serious problem for horses and birds.
There is a real cost to unreasoning fear of technology..
Posted by: David Moelling on September 18, 2006 1:51 PMTim Lambert's views on DDT have been systematically demolished at JF Beck's RWDB blog (see for example)
It's not libel if it's true!
Vast majorities of environmentalist groups see only anthropegenic causes to problems and believe that anything anthropogenic is by definition bad if not evil. VEHEMENT, ELF, ALF, SHAC, and PETA are extremists but do represent a strong thread in enviro and leftist politics that dislikes people, especially modernism and westernism. They do take a paternalistic liking to tribal groups, until they realise that the Noble Savage in tune with nature is a myth, if not a lie.
Greenpeace is responsible for killing millions of African babies Tim. The question is: do you only hate black people, or all people?
Leftism: taking out one's dislike for the poor on the poor by claiming to help them for 150 years!
Tim, do you share George Galloway's view that that day in 1991 when the USSR fell was the worst day in your life? Have you looked into people's actual behaviour, rather than what they ideally should do? Does species protection save animals or encourage "Shoot, shovel, shut up"?
One can be against environmentalists while sharing the goal of a cleaner environment. Things simply work better, and liberty is less impaired, when you use voluntary programs (like buying land you want to conserve, or paying for pollution control) rather than using the guns of the state to control behaviour. Unfortunately leftists love the revolution and yearn to be behind the barrel out of which power comes, as the Chairman said.
Posted by: Hey on September 18, 2006 2:27 PMJCR,
That was one helluva thread you linked to. Tim Lambert looks like someone who has a damn-the-facts agenda instead of someone looking to actually help people.
Posted by: happyjuggler0 on September 18, 2006 3:35 PM"Paul: From what I've read, it doesn't break down in nature, and in certain food chains, large amounds of the pesticide can build up in certain predatory species."
I'm not sure whether humans are considered a predatory species (it probably depends on who you ask). But, as I already pointed out, the use of DDT as a pesticide in China has led to the buildup of DDT in HK women, which was then passed on to their babies through breastmilk. What we heard in Hong Kong was that DDT was very hard to wash off - we scrubbed our vegetables pretty hard, but still worried.
Posted by: Ann on September 18, 2006 4:00 PMFrom what I've read, it doesn't break down in nature, and in certain food chains, large amounds of the pesticide can build up in certain predatory species. Birds of prey were especially susceptible to DDT buildup, and it caused thinner eggshells and fewer eagles.
I'm not sure whether humans are considered a predatory species (it probably depends on who you ask). But, as I already pointed out, the use of DDT as a pesticide in China has led to the buildup of DDT in HK women, which was then passed on to their babies through breastmilk. What we heard in Hong Kong was that DDT was very hard to wash off - we scrubbed our vegetables pretty hard, but still worried.
Okay, thank you. Thank you very much.
Next question for the masses: if this is all true and these bad things happen with DDT, do you believe that the pluses outweigh the minuses, or is it best that we not use it?
Posted by: Paul on September 18, 2006 4:06 PMI think that the costs of using of DDT as an agricultural pesticide outweigh its benefits. Large amounts of DDT cause harm to many species.
The carefully targeted use of small amounts of DDT to spray the inside of homes and buildings in malarial zones seems to have a benefit far outweighing the cost. In fact, in this latter context, it is unclear if there is any cost beyond that of the material and labor costs necessary to do the spraying.
The issue isn't whether it builds up in fatty tissues, it's whether that build-up is harmful. It certainly is to raptors (eagles, hawks, vultures, condors), because a high level of DDT causes their eggshells to be perilously thin. That effect does not seem to apply to any other kind of bird.
As for humans, I haven't seen studies proving actual harm. Anecdotally, I know of WWII and Korean war veterans that took very heavy doses. The army used to issue DDT foggers to clear camps of insects; noting that the fogger got cold as the contents evaporated, they would put their beer cans around the fogger, and then drink not-quite-as-warm beer in a fog of DDT. Others would actually spritz a little DDT in a shot of hard liquor, to give more of a buzz. That they didn't get sick right then and there supports the claim that DDT is not immediatly poisonous to humans, unlike most alternative insecticides.
OTOH, there could be long term effects, although I'd think that those former soldiers would have been carrying quite a load of DDT for many years and most of them remained quite alright. There is also the possibility that it affects children or fetuses through developmental pathways that are shut down in adults. It's hard to disprove that possibility (for anything, not just DDT) because no one wants to run controlled experiments, which would deliberately expose children or pregnant women to the substance in question. Field studies of children who just happened to have been exposed have the problem that they've probably been exposed to many other chemicals as well. Anyway, if there are effects of low dosage exposures, they are certainly much smaller than the effect of malaria!
Anyway, the best reason for discontinuing the widespread agricultural use of DDT wasn't to save the eagles, but because insects were becoming immune to it. That requires periodically switching insecticides, even when the alternates are more expensive and well-known to be more dangerous. (I grew up on a farm, and when we had to be in a fog of the newer, less environmentally damaging insecticides, we wore gas masks and rubber suits.)
The use contemplated now is a thousandfold less - spraying a little in the house and impregnating mosquito nets. Even if half of that gets diverted to unapproved uses, it shouldn't put enough into the environment to kill off eagles. (Here's hoping that somehow we do manage to preserve enough habitat that they don't die out anyhow.) It's possible that keeping DDT residues in houses all the time could cause mosquitos to develop immunity to DDT, but since each new mosquito generation will be mostly the descendants of mosquitos that bit an animal instead of risking DDT poisoning to bite a sleeping human, I think it far more likely that they'll just evolve towards avoiding the scent of DDT, humans, or houses. OTOH, cockroaches and any other insects that live their lives in houses will definitely evolve immunity, so new ways of killing them will always be needed.
Posted by: markm on September 18, 2006 5:03 PMComing back to the origianl point, read the NYT article I link and you'll see strongly pro-DDT statements from Bush's head guy on malaria and from Sen Tom Coburn.
So, it's a statement of fact that the US is pushing DDT. I didn't draw any implication of commercial self-interest from the fact and it's silly of you to put one in my mouth.
As the thread above indicates, lots of people in the US, mostly on the right, think DDT spraying is a cure-all. This leads the US government to be willing to fund DDT spraying in preference to other, perhaps more cost-effective measures.
Posted by: John Quiggin on September 18, 2006 5:04 PMCan any of my readers comment?
If Bush is for it, Quiggan is against it. African lives be damned.
Posted by: A.S. on September 18, 2006 5:22 PMThe way I read it, the conflict was the politicial pressure of the US vs. "the science". It seemed to me to imply that "the science" argues against the use of DDT. Usually when someone is taking a scientifically ridiculous stand, it's because of self-interest, of which the US doesn't appear to have any in this battle. I wasn't putting words in your mouth; I was asking my readers what political interest the US has in pushing DDT on the third world. Tim Lambert's answer is that it is a vast right-wing conspiracy against the environmental movement, which seems possible but not exactly probable to me--though perhaps it looks different from the other side of the planet.
Perhaps what you meant so say was that the scientific opinions of the donors are generally the ones that get followed? This is certainly true of almost anti-malarial programmes.
Posted by: Jane Galt on September 18, 2006 5:24 PMThe way I read it, the conflict was the politicial pressure of the US vs. "the science". It seemed to me to imply that "the science" argues against the use of DDT. Usually when someone is taking a scientifically ridiculous stand, it's because of self-interest, of which the US doesn't appear to have any in this battle.
There is no self-interest in this battle on the part of the United States, unless you think that wiping our Malaria in Sub-Saharan Africa (Bald Eagles and Environment be damned) will have some net positive effect at helping to stop Malaria here in the United States. Personally, I think Senator Coburn is proposing this not from a selfish standpoint, but because deep down he thinks it is the right thing to do. No more, no less.
Posted by: Paul on September 18, 2006 5:48 PMThe link I posted at RWDB doesn't seem to be working anymore - try this one
http://rwdb.blogspot.com/2006/07/ddt-expert-debunked.html
Posted by: stephen c on September 18, 2006 6:39 PMAnti-malarial bednets are a bother to use, necessary to be used exactly when you least feel like putting in the effort, vulnerable to wear and tear, and easy to reduce in effectiveness through misuse.
The result is that comparing bednets and spraying as forms of malaria control are like comparing condoms and Norplant as methods of birth control. Yes, condoms can work, but Norplant works much better as birth control; nobody suggests condoms over Norplant on the basis of effectiveness at preventing pregnancy, but only for other factors. And those who really care about preventing unwanted pregnancies don't propose condoms as the end-all, be-all solution.
DDT vs. other spraying cost-benefit analysis is a decent question. But the bednet armies are of those so fixed against spraying that they're willing to stop spraying in exchange for more cases of malaria.
Posted by: Anonymous on September 18, 2006 7:29 PMJane, I did not say that it was a vast right-wing conspiracy. Most of the people blaming environmentalists for malaria genuinely believe that its all Rachel Carson's fault, even though that is not true. Coburn's political interest is to attack environmentalists. That doesn't mean that he doesn't also believe that he is saving lives, but the politics behind his actions are pretty obvious.
Posted by: Tim Lambert on September 18, 2006 9:22 PMI think the formatting is unclear and unfair to John Quiggin. What he says is "This is being trumpeted as a huge change, but is actually a change from one moderate DDT policy to another DDT policy. It's not even clear if this moderate change is justified." When I see the page, the first half of what he says looks like Jane Galt's own gloss on Quiggin, which obscures the fact that the motivating question is "why are wingnuts making this out to be a huge change, when it is really a moderate change that may not even be the most cost-effective strategy?". (I think the comments on this blog prove that a certain kind of person *is* convinced this is equivalent to the DDT Reconquista...
Posted by: gruad on September 18, 2006 10:26 PMBasically, everything you think you know about DDT is wrong. It has not been linked with any health problems in humans and, specifically, is not a human carcinogen. It does not, Rachel Carson to the contrary notwithstanding, effect songbirds. There is no correlation between either raptor egg thinning or raptor populations and the use of DDT.
Stopping DDT led to the deaths of millions of people who did not have to die.
Posted by: David Cohen on September 18, 2006 10:45 PMTim Lambert wrote:
Coburn's political interest is to attack environmentalists. That doesn't mean that he doesn't also believe that he is saving lives, but the politics behind his actions are pretty obvious.
What exactly does "Coburn's political interest is to attack environmentalists" mean? Please provide some evidence of this. Note: Postings on left leaning blogs do not, by themselves, constitute evidence.
Allow me to suggest a different nefarious motive to Senator Tom Coburn - he is a medical doctor and may be interested in the practice of public health.
Posted by: Kevin P. on September 18, 2006 10:59 PM
As you can see from the thread, the US position is driven by uninformed people like David Cohen, who get their information from the rightwing blogosphere or from shills like Steve Milloy.
The abandonment of area spraying of DDT was driven by the development of resistance. No-one serious is proposing that it be reintroduced. The issue now is about the circumstances in which spraying of interior house and hut walls should be recommended.
"No-one serious is proposing that it be reintroduced". Ah yes, just like "no REAL, RESPONSIBLE scientist doesn't believe in man-caused global warming".
In fact, when Ruckelshaus(sp?) banned it, he admitted that he never read the research; he just decided to do it.
Posted by: Firehand on September 18, 2006 11:36 PMKevin P, why do you find it so hard to believe that a politician might have political reasons for his actions?
Posted by: Tim Lambert on September 19, 2006 12:44 AMJohn Quiggin just lost his right to criticise creationists.
Posted by: Anthony on September 19, 2006 3:46 AM
Comments like those of Firehand are doing a great job of proving the point - it's notable that most commenting in this vein raise global warming as well.
Tim Lambert:
Kevin P, why do you find it so hard to believe that a politician might have political reasons for his actions?
I'll take this as an admission that you can't find any specific political actions for the pro-DDT position taken by a physician in the Senate :-)
I am fully willing to believe that a politician might take a position for political gain. As do environmentalists and bloggers. And, just occasionally, all of these people might take a position in good faith for what they see as the right reason for the right cause. Try assigning some reasonable motives to your opponents every once in a while. It is not that difficult and you will come across as less obsessive and paranoid.
Posted by: Kevin P. on September 19, 2006 7:46 AM4000 tons/year of DDT, is this something that is level, slowly rising, or rapidly rising? According to the EPA, the US averaged 22,500 tons/year of DDT between 1945 and 1975, so 4000 tons/year sound high for low concentration indoor spraying, but rather low for extensive agricultural pesticide use.
Posted by: Sam on September 19, 2006 9:32 AMJohn Quiggin:
You do realize that DDT did lead to malaria being wiped out in the American south, right?
In any event, it takes a study to beat a study. Where, exactly, are the peer reviewed double-blind studies that show that DDT is a human carcinogen, or an egg-shell thinner, or that its use would kill all the songbirds resulting in a silent spring?
I am not advocating that DDT be reintroduced as an agricultural pesticide, which, as you say, no one is suggesting. I am saying that it is still the most effective, and cost effective, way of stopping the spread of malaria in poor countries, with minimal harm to the environment.
Resistance is a red-herring. Some mosquitoes are resistant. Once the non-resistant mosquitoes are killed, the resistant mosquitoes will eventually build the population back up. But the point of DDT is not to get rid of mosquitoes but to get rid of malaria. Resistance does not effect that use.
First, even resistant mosquitoes are averse to DDT. They will leave a treated house, even though the DDT won't kill them. Second, the malaria parasite can only life in human blood. It lives for about three years. Between the first use of DDT to devastate the population and the rebuilding of the resistant population, enough time usually elapses to wipe out malaria -- as in fact happened in the American south. Third, it was probably agricultural use, rather than anti-malarial use, that gave rise to resistance. Again, no one is suggesting bringing back agricultural use.
Finally, you completely fail to deal with the indisputable fact that millions of people have died from malaria who would not have died had DDT been used. What benefit have we received in return? I should note that, in the 50s, one of the arguments made against DDT use in the third world was, explicitly, that it would save too many people, thereby increasing overpopulation, poverty, disease, etc. You're not one of those environmentalists who thinks that the best thing mankind could do for the environment is to die off by the billions, are you?
Posted by: David Cohen on September 19, 2006 9:47 AM" 4000 tons/year sound high for low concentration indoor spraying, but rather low for extensive agricultural pesticide use."
As I understand it, DDT is officially banned for pesticide use in China, so presumably it's not their main pesticide (especially since they also produce other substances that are banned for pesticide use but still show up). The problem is that the central government in China, though brutal and authoritarian by inclination, is corrupt and has little power in most provinces. So State-Owned Enterprises produce banned pesticides and they somehow get out on the black market, where they are used by possibly semi-illiterate farmers that don't read or don't trust the directions, which probably aren't designed for pesticide use anyway. And perhaps illegal pesticides are used most in the south, far from Zhongnanhai in Beijing but where they can sell the produce to Hong Kong.
"Field studies of children who just happened to have been exposed have the problem that they've probably been exposed to many other chemicals as well."
In terms of short term problems, in Hong Kong we heard periodically of people being hospitalized for getting too many pesticides on their vegetables, as I said before. But as you say, it's hard to tell if their illness was due to DDT or to some other pesticide, since they probably got exposed to more than one.
Posted by: Ann on September 19, 2006 10:47 AMJane, Quiggin makes it quite clear to distinguish the possibly valid use of limited DDT in indoor areas to prevent malaria, and the 'DDT myth' so loved of the right that a worldwide ban on DDT was imposed and this caused many deaths.
DDT if used wisely is bad news for humans and the environment. DDT used in a targeted fasion indoors is worth exploring.
DDT if used wisely is bad news for humans and the environment.
I love Freudian slips, don't you?
Posted by: Person on September 19, 2006 11:26 AMQuiggin's assertion that Cohen is wrong (because of those bad old "right wing" blogs and "shills", and of course due to being "uniformed", which appears, in the absence of the provision of evidence, to be mere code for "disagreeing with John Quiggin") is not very powerful - though to be fair, Cohen's assertion that DDT is proven safe is also not overpowering, even though I tend to agree with his conclusions.
So how about we get some links to the studies themselves, or their abstracts?
Primary sources, people!
(Further, contra Quiggin, it's neither revealing nor surprising that Global Warming gets brought up in these discussions.
The relation is obvious to both sides, though the interpretation as to the reasons and rightness for the connection is vastly different.
And, again, an assertion or implication that The Other Side Is Simply Ignorant And Wrong carries no weight in convincing the other side, or of showing one's own side to be correct.)
Posted by: Sigivald on September 19, 2006 12:30 PMFor the citations on thin eggshells, go to the "Conservation and Managment" section of the following account on the Peregrine Falcon, from the Cornell Lab of Ornithology. You will find that the research was done from 1967 through 1988, and thus mostly doesn't exist online, except in subscription-based archives. Hence the lack of citations, here.
http://bna.birds.cornell.edu/BNA/demo/account/Peregrine_Falcon/
The general result - DDT, or more properly a decomposed DDT called DDE, thins the eggshells of some bird species. It affects raptors, vultures, and ducks, but not chickens or, particularly, songbirds. The mechanism appears to be enzyme-based in the mother bird - the shells have the same calcium density as before, but not as much shell thickness is created in birds with high DDE concentrations relative to birds with low DDE concentration.
Songbird decline has little if anything to do with DDT - it has, in fact, accelerated in the last 20 years. Songbird decline is driven by habitat destruction, primarily on wintering grounds in Latin America and the Caribbean, and secondarily on migration routes and breeding grounds.
Widespread overuse of DDT did cause some issues with resistance, but the primary driver of the ban were the near-extinctions of certain large raptors - notably the Golden and Bald Eagles and the California Condor - and the significant reduction of the NA population of Peregrines.
Posted by: rvman on September 19, 2006 1:46 PMSigivald: My 10:45 post links, through the word "wrong," to a summary of the science on DDT. Under "egg shell thinning" it has a fairly exhaustive review of the literature. All of the laboratory studies that claim to show thinning involve massive doses of DDT while studies of thinned shells from the wild show no correlation with DDT.
Posted by: David Cohen on September 19, 2006 2:17 PMQuiggin shows his intellectual chops by indulging in ad-hominems and not addressing the specific complaints. My ad-hominems had the benefit of being snarky and with no intention to set myself up as an all knowing science God. Quiggin... not so much.
If you could, please explain why DDT is not widely used for residual spraying now in African countries. Since it obviously has nothing to do with left wing pressure to discourage its use, what was it? From your assertions we now all know that green groups do not and have never taken a misanthropic view towards environmental problems or wanted to stop or reverse population growth, thankfully, but we still remain unenlightened as to why DDT fell into disuse. Explain, please.
Or maybe you prefer to airily dismiss the "right wing" because we're on to you. But of course I'm an addle brained knuckle dragger, who couldn't possibly get anything right in terms of science or politics.
Posted by: hey on September 19, 2006 6:09 PMThe notion that DDT eliminated Malaria by itself in the American south is questionable. It's claimed by those who want to believe that DDT "bans" and the environmentalists who supported them killed millions. The bans which were passed (i.e. the Stockholm resolution) allowed use of DDT until replaced by more effective alternatives.
Regarding Malaria in the U.S. south; other factors were involved. The invention of air conditioning and better housing was HUGE in reducing the incidence of mosquito borne diseases in the US, particularly Malaria. Antibiotics also helped. DDT was a factor, but it wasn't the only factor. Even viral diseases like Eastern Equine Encephalitis are pretty rare here these days, even though the mosquitos which carry it are present.
DDT wasn't banned. Not in the US. Not in Africa. Not in Asia. It's use in the US was severely restricted, particularly for agricultural purposes. Which is a good thing. Since, as was mentioned, agricultural spraying of DDT encourages resistance. Europe has threatened Uganda that if DDT traces are found on Ugandan food, Uganda's produce will be banned. They've taken some heat for the threat, but it preserves DDT for mosquito eradication and prevents widespread environmental contamination, so it's for the best.
DDT is pretty safe in adult humans. The chemical itself isn't particularly harmful. the DDT metabolite, DDE, causes very minor liver damage. The blood brain barrier doesn't let large amounts of DDT through. As was mentioned, there are correlations between DDT in mother's breast milk and developmental problems including retardation, but it's hard to tie that to DDT specifically.
Resistance is not a red herring source though DDT still repels resistant mosquitos as mentioned. Reistance is widespread in Asia and some parts of the Americas, but not absent in some parts of Africa.
Posted by: Ryan on September 19, 2006 6:50 PMDDT seems to be a mild carcinogen, but very weak at the concentrations people are typicaly exposed to. source
The differential toxicity between humans and insects is pretty huge. Part of this is still an argument against widespread spraying though, since dragonfly adults and larvae are powerful mosquito control agents. If you see dragonflies near a body of water, chances are excellent you won't also see mosquitos. Area spraying of DDT kills dragonflies, promoting dependance on pesticides for mosquito control.
Finally, while there are far better methods of mosquito control (breeding dragonflies, releasing huge #s of sterile male mosquitos, releasing mosquitos which are resistant to P. Falciparum, etc.) insecticide treated houses and bed nets are by far the cheapest methods. And in areas like Africa, that's key.
Even those groups which tried to ban DDT are making an about face.
Spokesmen for Greenpeace and the World Wildlife Fund (WWF), activist environmental groups that have led the effort to ban worldwide use of the pesticide DDT, have admitted to the New York Times that DDT may be necessary and desirable after all.
"South Africa was right to use DDT," said WWF spokesperson Richard Liroff. "If the alternatives to DDT aren't working, as they weren't in South Africa, geez, you've got to use it. In South Africa it prevented tens of thousands of malaria cases and saved lots of lives."
Greenpeace spokesperson Rick Hind agreed. "If there's nothing else and it's going to save lives, we're all for it. Nobody's dogmatic about it."
Posted by: Ryan on September 19, 2006 6:51 PMShould read: "Reistance is widespread in Asia and some parts of the Americas, but absent in some parts of Africa."
Posted by: Ryan on September 19, 2006 6:52 PMI was wondering how long I'd have to scroll to get to some actual cited information that focuses on the real questions about the use of DDT in this way: resistance. Thanks.
Posted by: Josh on September 20, 2006 1:08 PM"Not addressing the specific complaints"
If the massive work of the IPCC on global warming and the detailed exposure of the network of industry-funded shills on the other side hasn't convinced you, I can't imagine what I could write or link to in a comments thread that would do so. Similarly for DDT.
Posted by: John Quiggin on September 20, 2006 11:33 PMJohn Quiggin:
...industry-funded shills...
Oh, please. This charge is the last refuge of the loser. You can do better than that. Try to convince people, not smear their motives. The smear game can works both ways. Environmentalists are interested in preserving their constituency, funding, political power and relevance. Climate scientists, like all researchers are interested in more funding, reputation and influence.
Argue the science and the evidence.
Posted by: Kevin P. on September 21, 2006 8:54 AM