Biology Science

Skeptoid disappoints about DDT and the environment

You may have noticed that there wasn’t the usual 3,000 word heapin’ helpin’ of Insolence this morning. That’s because I happened to be away visiting family in Chicago over the weekend and I just didn’t have time to come up with anything–and I enjoyed myself too thoroughly to worry overmuch about it. In case you’re wondering, the posts that went up over the weekend were either written before I left or so short that they took me five or ten minutes to do.

Sort of like this post.

Unfortunately, this morning I did see something of interest that disappointed me enough that I took a bit of time to compose this. I normally love Brian Dunning’s Skeptoid podcast. In general, it’s thorough, well-written, and Brian is interesting to listen to. I listen pretty much every week, and on weeks when I miss the podcast I usually catch up the next week. Unfortunately, occasionally even Dunning screws up. Occasionally he screws up big time. Like his podcast from three weeks ago, for instance, on DDT, which caused me to cringe as I listened to it. Indeed, I had even thought of blogging it at the time, but my expertise isn’t sufficient to cover the topic as well as I normally like to cover my topics.

Fortunately, there is fellow ScienceBlogger Tim Lambert. As Tim shows, in this case Brian Dunning used Steve Milloy of as a major source for his information that he used to try to paint the picture of DDT not being all that bad for wildlife and to trash Rachel Carson. Tim’s posted part I of what promises to be a two-part Skeptoid fact check. It’s depressing reading, particularly because Dunning should know better. Particularly disturbing is Dunning’s response to criticism that Milloy is a well-known corporate apologist whose positions nearly always align with corporate interests and who is well known for distorting science to defend said interests:

The JunkScience guy has a blatant libertarian agenda. The SourceWatch guy has a blatant anticorporate agenda. Big whoop! They’re both still researchers. I have no problem citing either if they’ve done the research I’m looking for.

If you must insist that this makes everything coming from either guy always right or always wrong, then you should demand to see the voting history of every scientist or researcher in order to determine the quality of their work.

As Tim points out, although it is true that all sources have some biases and usually aren’t wrong about everything (indeed, even Milloy gets it right when it comes to slapping down anti-vaccine idiocy), Dunning completely missed the point. He didn’t exercise proper skepticism regarding Milloy’s claims about DDT, virtually all of which are erroneous or exaggerated. As if his post weren’t enough rebuttal to the numerous egregious errors in Dunning’s DDT installment, Tim also has an extensive library of previous posts on the topic of DDT and Steve Milloy’s frequent distortions of science and has pointed to other sources taking down the myths about DDT that are out there, especially Milloy’s misinformation. Then there’s Bug Girl’s extensive listing of material showing the misinformation and distortions of science used to support the idea that severely restricting DDT use showed how radical environmentalists somehow care more about birds than people and/or that DDT isn’t nearly as bad as environmentalists paint it to be.

Color me profoundly disappointed. Here’s hoping Dunning takes Tim’s fact check to heart and doesn’t make such an enormous mistake again.

By Orac

Orac is the nom de blog of a humble surgeon/scientist who has an ego just big enough to delude himself that someone, somewhere might actually give a rodent's posterior about his copious verbal meanderings, but just barely small enough to admit to himself that few probably will. That surgeon is otherwise known as David Gorski.

That this particular surgeon has chosen his nom de blog based on a rather cranky and arrogant computer shaped like a clear box of blinking lights that he originally encountered when he became a fan of a 35 year old British SF television show whose special effects were renowned for their BBC/Doctor Who-style low budget look, but whose stories nonetheless resulted in some of the best, most innovative science fiction ever televised, should tell you nearly all that you need to know about Orac. (That, and the length of the preceding sentence.)

DISCLAIMER:: The various written meanderings here are the opinions of Orac and Orac alone, written on his own time. They should never be construed as representing the opinions of any other person or entity, especially Orac's cancer center, department of surgery, medical school, or university. Also note that Orac is nonpartisan; he is more than willing to criticize the statements of anyone, regardless of of political leanings, if that anyone advocates pseudoscience or quackery. Finally, medical commentary is not to be construed in any way as medical advice.

To contact Orac: [email protected]

44 replies on “Skeptoid disappoints about DDT and the environment”

As a malaria researcher and environmentalist, I am profoundly conflicted when I hear the DTT ‘skepticism’ stuff. I’d really appreciate if you’d link to any detailed debunking on this topic you happen to know of. Not asking you to do my homework out of laziness, I’d really like to know what you consider a credible source here.


I’d second that. I’ve always understood DDT as being quite bad for the environment, but damn if it didn’t work well to stop malaria in its tracks in the U.S.


but my expertise isn’t sufficient to cover the topic

But that doesn’t stop you from blogging about vaccination.

This is one of the things I love about the skeptical community: we aren’t afraid to call out our own when they’re wrong.

Me too. In fact, I had the chutzpah to call Randi himself out when he went so wrong on global warming…

Todd: Yeah, DDT was so effective against malaria in the US that it actually traveled back in time and reduced the number of cases by 90% (eradicating the disease from huge swathes of the country) before DDT was ever used as an insecticide.

DDT was only the last element in the eradication of malaria from the US. Most of the work was done prior to its introduction during WWII via source reduction, window screening and early larviciding techniques.

Resistance was long a problem with DDT and mosquitoes. The first confirmed case was a population of Aedes taeniorhynchus on the east cost of Florida in 1948 and by the end of the 1950s, most US mosquito programs had stopped using it.


but my expertise isn’t sufficient to cover the topic

But that doesn’t stop you from blogging about vaccination.

I realize Sid is just trolling as usual, but he accidentally raises an important point.

There are some skeptical issues where the required expertise is just not all that complicated. Vaccines are one of them. Creationism is another. Yes, the details of how vaccines work are very complicated, and the details of evolutionary biology are very complicated — but one does not need a whole lot of expertise to be able to see that vaccines are a net benefit, or that some sort of evolution via natural selection must have occurred (and that Creationism is a silly stupid idea in comparison).

Other issues are harder. AGW comes to mind as the immediate example. It is easy for me to understand that CO2 functions as a greenhouse gas, but it is difficult for me to understand how the magnitude of human CO2 emissions relates to that, and what the climate consequences will be of a given amount of CO2 concentration in the atmosphere. The science here is really complicated. I need to cede to the experts on this one. I cannot make the case myself, nor can I handily debunk the claims of AGW deniers. (And no surprise, we see a lot more dissent amongst the skeptic community regarding AGW, I think for exactly that reason. IMO the skeptical position is still to trust the overwhelming consensus of the experts, but it is not surprising to me that not everybody gets it)

The cost-benefit of DDT is yet another complicated issue, especially when you are talking about using it in a place where malaria is rampant. I can grasp pretty easily the idea that it weakens the shells of bird eggs, and that it accumulates in the environment (much the same way that mercury does) because of the very slow rate at which it is metabolized. But I cannot very easily quantify the impact of that, nor can I quantify how well it works to prevent malaria and how effective the alternatives are. My impression –largely based on trusting “the experts”, because what else can I do? — is that there is a place for DDT in areas afflicted with a serious scourge of malaria, but that it’s use ought to be highly restricted and probably not used at all in areas where malaria is not a big issue. But I don’t really know, any more than I know one model of carbon emissions from the next.

What anti-vax trolls like Sid fail to realize is that the expertise required to see that vaccines are beneficial is not particularly challenging. Which is why there is virtually unanimous agreement amongst the skeptical community in regards to that issue.


Agree. I prefer to get the straight dope on vaccines from someone who has no medical or scientific understanding but does make a cameo appearance in a college statistics textbook [exercise 1.11] as a teaching point on how to skew survey results.

For malaria endemic areas, DDT is still one of the materials listed by WHOPES (WHO Pesticide Evaluation Scheme) for use as an IRS (Interior Repellent Spray), under restrictions specified by the Stockholm Convention. Primarily, this is when there is a lack of viable alternative and there is no local resistance. There are very specific requirements to prevent diversion to other uses and there are specific techniques required for cleaning application equipment and collection of rinsate.

@wintermute and the bug guy

Thanks for the responses. Just goes to show how a popular, but totally mistaken, idea can survive and spread. I suppose I should’ve looked about a little more first. If I had, I might have found more information, like this article by bug girl.

Fortunately, there is fellow ScienceBlogger Tim Lambert.

Riiiiiiiiiiight, well-known Warmista propagandist Timothy “Lamebrain” Lambert of Dulltard, a computer scientist (with a Master’s degree!), which makes him an Expert on EverythingTM. Just ask him.

Milloy is a well-known corporate apologist whose positions nearly always align with corporate interests

Yes, it would be much better to get a government apologist, wouldn’t it? Government good, corporations bad. In fact, let’s abolish all corporations and have everything run by government. It worked so well in the USSR, after all!

showing the misinformation and distortions of science used to support the idea that severely restricting DDT use showed how radical environmentalists somehow care more about birds than people and/or that DDT isn’t nearly as bad as environmentalists paint it to be.

Not to worry, Orac. Most of those extra deaths from malaria were Africans (read: not white). They are expendable in the name of radical environmentalism.

I had the chutzpah arrogance to call Randi himself out when he went so wrong on told the truth about global warming…

There, fixed that for ya, Orac. Don’t mention it.

Posted by: NJ | November 22, 2010 9:47 PM

Ah, yes, GWIAS doing a drive-by stupid. Couldn’t have seen that coming, could we?

Projecting, are we NJ? How pathetic! Entirely expected, however, coming from a GW religionist such as yourself.

How droll. GWIAS provides us with a random, and quite boring string of insults. It would have been more interesting to actually counter with something like data and evidence.

As pointed out in this thread, DDT was not the primary means of malaria control. Plus there was an issue with mosquitoes developing resistance to the pesticide (often due to overuse, see the book Mosquitoes, Malaria and Man, A History of the Hostilities Since 1880). There is, in fact, some interesting Genetic Engineering on mosquitoes to combat dengue (recently in the Nature blog, I am at my two link limit), and malaria.

So, GWIAS, do you have an intelligent comment on the article last week in the NY Times: New Hurdle for California Condors May Be DDT From Years Ago? Or are you going to do a “Little Augie” and just put in some odd insults and re-write what I wrote?

It’s pretty clear now that using DDT to improve cotton yields was not the best thing that could have been done with DDT.

Not using DDT against malaria mosquitoes was one of the worst things that could have been done.

Carson was not a big picture person, was she? I take James Sweet’s point but think it wrongly applied to climate. It isn’t difficult to determine that all claims of the form ‘the world in 2010 is X degrees warmer than 1910’ are bogus.

Harry Eager:

Not using DDT against malaria mosquitoes was one of the worst things that could have been done.

I see you have not been paying attention. I suggest you read the Washington Post article posted by MZ. Especially the paragraph that says:

What people aren’t remembering about the history of DDT is that, in many places, it failed to eradicate malaria not because of environmentalist restrictions on its use but because it simply stopped working. Insects have a phenomenal capacity to adapt to new poisons; anything that kills a large proportion of a population ends up changing the insects’ genetic composition so as to favor those few individuals that manage to survive due to random mutation. In the continued presence of the insecticide, susceptible populations can be rapidly replaced by resistant ones. Though widespread use of DDT didn’t begin until WWII, there were resistant houseflies in Europe by 1947, and by 1949, DDT-resistant mosquitoes were documented on two continents.

Actually, yellow fever was mostly conquered in the Panama Canal Zone before WWII. That was a good part of the book Panama Fever: The Epic Story of One of the Greatest Human Achievements of All Time– the Building of the Panama Canal.

Yes, but its use was also restricted in places where it was still working. In some cases, the reason it wasn’t still working is that it was overused against targets other than malaria mosquitoes.

If you look at a map, malaria was eradicated in rich countries and persists in poor countries. Recent problems with dengue show an exactly similar pattern.

Some people get the big picture, some don’t.

GWIAS @ 17:

Projecting, are we NJ? is the only thing I can do. How pathetic! Entirely expected, however, coming from a GW religionist such as yourself simple-minded denialist as me.

Fixed for you.

novalox @ 20:

And using ad homiem attacks helps your position in what way?

Realize that it’s all he can do. He has no data, no science, no thing whatsoever, except his tribal identity. And the leaders of his tribe tell him reality is wrong, so he believes it. Fundamentally he isn’t any different from the Heaven’s Gate followers.

Read the Washington Post article: “By 1972, when the U.S. DDT ban went into effect, 19 species of mosquitoes capable of transmitting malaria, including some in Africa, were resistant to DDT.”

Read the article about Gorgas: “Elimination of the disease by this method proved a Sisyphean task. Fortunately for Gorgas, the city was under military rule and that made it much easier to carry out his orders.”

Which African countries have the cash to drain swamps, quarantine people, have very strong public health agencies, force clean up and spray with the other insecticides? Or even a disciplined military force?

The malaria, and dengue are complicated. There is no simple answer. Using DDT as a cure-all is not going to work. Check out the CDC Malaria Map Application. Did you notice that not every African country has malaria? What do most of the countries with malaria have in common?

A stable government? A good economy? Easy access?

Trust me, I am freaked out by the spread of dengue fever. I acquired dengue fever in the Venezuelan country side forty years ago. It would not be a good thing for me to get again.

Oh, and another memory I have as a little kid: running behind the fog sprayers in Ft. Jackson, SC. Yikes!

(I was an Army brat, and even lived in Panama and have been in Gorgas Hospital, visiting patients and getting some blood tests when I had pneumonia)

Carson was not a big picture person, was she?

To the contrary, she was. Silent Spring was about the big picture. Oh, and contrary to the smear campaign, she supported the continued us of DDT for vector control.

American Entomologist had an excellent review (Professional Entomology and the 44 Noisy Years Since Silent Spring) a couple of years ago in the Winter 2006 and Spring 2007 issues

Not to worry, Orac. Most of those extra deaths from malaria were Africans (read: not white). They are expendable in the name of radical environmentalism.

When DDT was heavily used, there were three million deaths per year from malaria, most of them African. Now that we’ve switched to other methods of malaria control (including limited DDT use, where it still works), that’s down to one million deaths per year. Do you think that saving two million not-white lives per year is a bad thing? Or do you just refuse to look at the most simple statistics?

In related news, India uses some four-fifths of the world’s DDT for malaria control. They also have one of the highest rates of death from malaria, with over 200,000 deaths per year. Why do you want other countries filled with non-white people to emulate such a disastrous strategy? How many preventable non-white deaths are you OK with, so long as the Holy Grail of increased DDT use is achieved?

With fish populations, water tables, soil fertility, etc already declining explain to me again why we need to release DDT. Ohh to increase human populations. Yea go team go.


Mike, with disease control and rise of living standards the population level tends to stabilize. That is because a parent does not have to have so many kids in hopes that one or two will live to take care them when they are old.

Dunning is a Libertarian and his “skepticism” takes a backseat to his political views. If the prevailing scientific view conflicts with his ideology then ideology trumps science. He isn’t any more a skeptic than Jenny McCarthy is.

Other ideas to take a back seat to skepticism were climate change and organic farming since those concepts don’t play well for the Libertarian crowd. But Dunning has a podcast and with a microphone that gives someone instant authority on any subject.

This is getting kind of old. I always ask for feedback and corrections to my episodes, and on this one I sent out special requests for corrections to address all the criticism. So far I’ve received a grand total of exactly 2 corrections. Both were immediately posted, and neither was very substantive; certainly neither affected my conclusion that the current DDT bans are appropriate everywhere except Africa. I continue to be surprised at how incendiary this conclusion was. was never a source. It was a Further Reading suggestion posted after the episode was recorded. Every Skeptoid episode attempts to have Further Reading suggestions that cover the full spectrum; I also continue to be surprised at how angry people are about this suggestion. Nobody raises such ire when I list Alex Jones or David Icke when I do an episode about conspiracy theories. Why not? They’re not equally nutty?

I’ve read the page on DDT, and I’ve found 2 points it makes that I also made. First, that Texas pelican populations had been decimated by hunting by fishermen, and second, that some environmental groups oppose malaria donations that include the use of DDT. As far as I can tell, these are both true. This is Skeptoid’s horrific fail? Are you kidding me?

I repeat my plea to send me any corrections. “Steven Milloy is terrible” does not constitute a correction; I couldn’t care less what your opinion of him is, as he was not mentioned and was not a source for the episode. Email your corrections to [email protected]. If they’re verifiable they will be posted with pleasure as have the others. If you don’t have a correction, I marvel at how upset you all seem to be.


In this post, I linked to a detailed critique of your DDT post, and you have the chutzpah to claim that I didn’t point out a single error? What do you want me to do? Repeat each error in the posts that that I linked to?

The critique is here:

Part 2 is here

That’s not all, either. Bug Girl post a detailed rebuttal of the same sorts of fallacious arguments you repeated:

A word of advice from a fellow skeptic: I humbly suggest that you should do one of two things. Either you should just suck it up and admit you screwed up, apologize, and then move on. Your continuing to defend so many errors and the use of JunkScience as a source only hurts your reputation. Your listeners, including me, would be quick to forgive and forget. As you know, reputation is precious; it takes long years of hard work to build but can be seriously damaged by just one mistake. I’d hate to see that happen to you and Skeptoid over the DDT episode. Alternatively, you need to directly address Tim Lambert’s and Bug Girl’s criticisms rather than complaining about how we’re all being so unfair to you.

P.S. Please stop denying that JunkScience was one of your sources. In part 2 of his deconstruction, Tim shows pretty conclusively that you all but admitted that you used Junk Science as a source. Moreover, your excuses for having listed it as “further reading” while not having used it as a source are unconvincing to me. The resemblance between your arguments and Steve Milloy’s dubious arguments is just too uncanny. In any case, it boggles my mind that you weren’t previously aware of Milloy’s reputation for distorting science in the service of industry interests, particularly in the areas of global warming, secondhand smoke, food and obesity, and defending indefensible practices of the pharmaceutical industry.

Actually, Milloy has attacked science finding that smoking itself is dangerous. For instance, in 2003, Tobacco Weekly wrote:

Steven Milloy, author of, also criticized the Centers for Disease Control and Prevention for claiming that 400,000 people die every year from alleged smoking-related illnesses, saying that studies linking smoking to heart disease are not entirely reliable. He pointed out that smokers have higher heart disease rates than non-smokers partly because smokers also tend to be people who do not exercise, have worse diets, avoid doctors and have less healthy lifestyles overall. (CNS News 8/1).

Not knowing just how bad a source Milloy is on almost everything was a huge blind spot for a skeptic to have, and I hope that this experience has educated you in that regard.

I personally sent Dunning a link to part 2 of my fact check and he had already commented on part 1. It is dishonest of him to claim that he has only been asked to make two corrections.

Mr Dunning: I corrected your “three million deaths a year” figure to one million in the episode comments. I even provided a source for you to check. As yet, the transcript has not been updated to include this. Can you explain why?

“Skeptoid’s Massive DDT Fail!”, Brian Dunning’s response to criticism at (, is itself a massive Skeptoid fail.

Before reading it, keep in mind that (a) asks for responses to episodes to be posted as comments, not sent in email, (b) the episode listed Steve Milloy’s DDT FAQ at as a source, (c) in response to criticism in the Skeptoid comments, Dunning said Milloy was “one of my sources,” (d) on Twitter, this exchange occurred:

Jim Lippard: Haven’t listened yet, but will. Is Milloy cited as a supporting source or a source of misinformation being corrected?

Brian Dunning: It’s where I got sources for the hunting of pelicans in Texas. It was not the original source, which I probably should have cited.

After reading it, read comments #21, #28, #41, #43, #18, and #8, and then look for Brian Dunning’s responses to the substantive criticisms in those comments. So far, nada.

Here are some references regarding DDT and human/environmental health. While no one would argue (at least no one I know) that DDT should be used in an agricultural setting, there is no clear evidence that indoor residual spraying is causing significant environmental or health problems. Despite very large body burdens of DDT/DDE in people where DDT is used for indoor residual spraying, no definitive population-level effects have been established. Many sources point to a correlation between DDT or DDE and health problems, but none show causation. I agree that the people exposed to DDT for vector control should be informed if evidence exists that they are in danger, and that scientists should continue epidemiological studies investigating the endocrine-disrupting ability of DDT/DDE. But one who unquestioningly supports one side or the other does so at the expense of disregarding research to the contrary.

Aneck-Hahn, N. H., G. W. Schulenburg, et al. (2007). “Impaired Semen Quality Associated With Environmental DDT Exposure in Young Men Living in a Malaria Area in the Limpopo Province, South Africa.” J Androl 28(3): 423-434.

Blus, L. J., S. N. Wiemeyer, et al. (1997). “Clarification of effects of DDE on shell thickness, size, mass, and shape of avian eggs.” Environmental Pollution 95(1): 67-74.

Bornman, R., C. De Jager, et al. “DDT and urogenital malformations in newborn boys in a malarial area.” BJU International 106(3): 405-411.

Cohn, B. A., M. S. Wolff, et al. (2007). “DDT and Breast Cancer in Young Women: New Data on the Significance of Age at Exposure.” Environ Health Perspect 115(10).

De Jager, C., N. Aneck-Hahn, et al. (2007). “DDT Levels and Seminal Parameters in Men: The Adverse Impact of Indoor Residual Spraying (IRS).” Epidemiology 18(5): S77-S78 10.1097/01.ede.0000276672.38588.f4.

Eskenazi B, Chevrier J, Rosas LG, Anderson HA, Bornman MS, et al. 2009 The Pine River Statement: Human Health Consequences of DDT Use. Environ Health Perspect 117(9): doi:10.1289/ehp.11748

Fernandez MF, Olmos B, Granada A, López-Espinosa MJ, Molina-Molina J-M, et al. (2007). Human Exposure to Endocrine-Disrupting Chemicals and Prenatal Risk Factors for Cryptorchidism and Hypospadias: A Nested Case–Control Study. Environ Health Perspect 115(S-1): doi:10.1289/ehp.9351

Fry, D. M. and C. K. Toone (1981). “DDT-Induced Feminization of Gull Embryos.” Science 213(4510): 922-924.

Gladen, B. C. and W. J. Rogan (1995). “DDE and shortened duration of lactation in a northern Mexican town.” Am J Public Health 85(4): 504-508.

Lee, D.-H., M. W. Steffes, et al. “Low Dose Organochlorine Pesticides and Polychlorinated Biphenyls Predict Obesity, Dyslipidemia, and Insulin Resistance among People Free of Diabetes.” PLoS ONE 6(1): e15977.

Longnecker, M. P. (2005). “Invited Commentary: Why DDT Matters Now.” American Journal of Epidemiology 162(8): 726-728.

Longnecker, M. P., M. A. Klebanoff, et al. (2002). “Maternal Serum Level of 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene and Risk of Cryptorchidism, Hypospadias, and Polythelia among Male Offspring.” American Journal of Epidemiology 155(4): 313-322.

Rignell-Hydbom, A., J. Lidfeldt, et al. (2009). “Exposure to p,p′-DDE: A Risk Factor for Type 2 Diabetes.” PLoS ONE 4(10): e7503.

Rogan, W. J., B. C. Gladen, et al. (1987). “Polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethene (DDE) in human milk: effects on growth, morbidity, and duration of lactation.” Am J Public Health 77(10): 1294-1297.

Schenker, U., M. Scheringer, et al. (2008). “Using Information on Uncertainty to Improve Environmental Fate Modeling: A Case Study on DDT.” Environmental Science & Technology 43(1): 128-134.

Tinwell, H., C. Friry-Santini, et al. (2007). “Evaluation of the Antiandrogenic Effects of Flutamide, DDE, and Linuron in the Weanling Rat Assay Using Organ Weight, Histopathological, and Proteomic Approaches.” Toxicological Sciences 100(1): 54-65.

Van Dyk, J. C., H. Bouwman, et al. “DDT contamination from indoor residual spraying for malaria control.” Science of The Total Environment 408(13): 2745-2752.

Verhaeghen, K., W. Van Bortel, et al. “Knockdown resistance in Anopheles vagus, An. sinensis, An. paraliae and An. peditaeniatus populations of the Mekong region.” Parasites & Vectors 3(1): 59.

Wolfe, N. L., R. G. Zepp, et al. (1977). “Methoxychlor and DDT degradation in water: rates and products.” Environmental Science & Technology 11(12): 1077-1081.

Zlotkin, E. (1999). “THE INSECT VOLTAGE-GATED SODIUM CHANNEL AS TARGET OF INSECTICIDES.” Annual Review of Entomology 44(1): 429-455.

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