Brian Dunning’s DDT Fail

A few weeks ago, Brian Dunning of Skeptoid posted a podcast that made a variety of claims about DDT and Rachel Carson’s book Silent Spring that were poorly researched and factually incorrect. For a while Dunning refused to admit his error; the podcast page as of 11/23/10 now has a box at the bottom in which he distances himself from the DDT claims he made by saying “Skeptoid is not here to tell you what to think.”

I and a few other people have been writing for several years about the way in which right-wing groups have been promoting DDT and attacking Rachel Carson. I could easily do a point-by-point fisking of Dunning’s mistakes (which others have done ably; see links at the bottom of this post), but I think the most useful thing to do would be to examine why a prominent skeptic fell so hard for a bogus manufactroversy.

Manufactroversy (mÄnâyÉ-făkâ€-trÉ-vûrâsÄ“). A manufactured controversy that is motivated by profit or extreme ideology to intentionally create public confusion about an issue that is not in dispute.”

You see manufactroversies all the time in the media– “Teach the Controversy!” “Global Warming is a hoax!” “Vaccines are poison!” The common thread is creating a controversy even though a clear consensus exists within the scientific community.

Media likes to frame issues as a debate: if you can get two talking heads to argue, that’s great TV. The problem is, presenting both sides of an argument is silly when there is no actual lack of consensus.

Dissent is manufactured by using information out of context and/or finding a scientist that opposes the prevailing view. That lone scientist’s opinions are then given equal weight to the majority of scientists who don’t think using DDT indiscriminately is a good idea. Or that Global Climate Change is a real and major threat to ecosystems.  You get the idea.

Manufactroversies also exploit the way in which scientists are constrained to speak in probabilities, not absolutes.  It’s part of the language of science to say that something may be true, almost surely IS true, but there are caveats on the conditions under which something is true. Scientists also have to make statements open to revision based on new information.

That’s part of what Skepticism is all about, too–forming opinions based on the available evidence.  New Evidence? Re-assess your conclusions.  This is not, alas, how many major media outlets–or politicians–operate.

The primary source Dunning seems to have used for his DDT fiasco is a website called Junkscience has an amazing history, and a little follow the money helps to connect cigarettes, lobbyists, anti-environmentalism, and an astroturf group called Africa Fighting Malaria.  Why didn’t Dunning pick up on those red flags? I don’t know.

The reality of DDT and malaria is that it is an incredibly complex problem.  There isn’t only ONE species of malarial parasite (Plasmodium). There isn’t only ONE species of malaria mosquito. There is not just ONE kind of ecosystem in which birds, mammals (including people) and malaria interact.  There is not just ONE political and health care system in areas where malaria occurs that is optimal for managing treatment.  In fact, in some areas where malaria occurs, there is no effective political or health care system!

Each system is different, and that is why blanket statements that portray DDT as a panacea for solving malaria problems are false and, frankly, stupid.  The issue of insecticide resistance is not trivial. We have many tools in our insect control toolbox; we need to choose each chemical carefully based on the best chance of control within a particular context. Making the wrong choice can have serious consequences if resistance occurs, and we loose the use of a pesticide.

When people espousing careful examination of data before making an insecticide choice are attacked for promoting “genocide”, you have to know something else is going on.  There is a political agenda at work.

I can guarantee you that within 24 hours of this post, there will be at least one, probably more, commenters that will accuse me of racism (“you want to kill brown people in Africa!”) or of lying about DDT.  They have shown up all over my blog whenever I bring up the topic of DDT and Rachel Carson.  Their primary methodology is copy/paste of the same old tired arguments over and over.

These are not people interested in nuance or conditionality of conclusions. They are people that find information that fits with their already existing world view, and then adopt it. Because it supports what they already believe.

Carson’s principal thesis was that broadly biocidal chemicals should not be carelessly introduced into the ecosystem.  She also said this: “It is not my contention that chemical insecticides must never be used.”  I don’t think many here would disagree with those statements.

Had Dunning actually READ Silent Spring, he might have realized his own words were wildly incorrect: “Silent Spring’s principal thesis was that DDT harms bird populations through eggshell thinning.”  In fact, the evidence for eggshell thinning was not published until after Carson’s death from breast cancer in 1964. (Also, when writing a critique of a book, it helps if you actually read the fucking book. But I digress.)

Dunning clearly got his information second-hand. And it was bad information.  This should be a lesson to all of us to check our sources carefully, and ask questions about “Who Profits?” and “What’s the Motivation?” about everything we read.  And to be willing to own it when we screw up.

Suggested resources:

The Science:

The Politics:


Bug_girl has a PhD in Entomology, and is a pointy-headed former academic living in Ohio. She is obsessed with insects, but otherwise perfectly normal. Really! If you want a daily stream of cool info about bugs, follow her Facebook page or find her on Twitter.

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  1. Oh snap! Brian Dunning might have caught the dread disease confirmationbiasitis, bane of the mostly rational everywhere! Is there a non-toxic cure for that?

  2. When I have a little more time this weekend, I’d like to put together a single page on the Bug Blog that collects even more of the DDT mythbusters info.

    Also, waiting for someone to point out the many times *I’ve* made a mistake…..That is the hardest thing about writing this post. There but for the grace of FSM…
    He was just so very wrong, I couldn’t leave it unchallenged.

  3. Dunning clearly got his information second-hand. And it was bad information. This should be a lesson to all of us to check our sources carefully, and ask questions about “Who Profits?” and “What’s the Motivation?” about everything we read. And to be willing to own it when we screw up.

    That’s the part that gets me about this whole incident. Brian has bragged before about his research technique and the network of people he has backing him up. It appears that on this topic he read one source and decided that it was good enough. He didn’t go back to the primary sources at all. He fell for the propaganda and didn’t do his research. I am very disappointed.

  4. I know little about this subject, so will start out by saying that I have no doubt you are right and there are many factual errors in this episode of Skeptoid, and that maybe Dunning even got caught by some confirmation bias and didn’t use enough sources.

    That said, I still think that the concluding paragraph to the episode is fairly sane and reasoned. His clarification paragraph even indicates he is going to fix his factual errors in one of his Things I Was Wrong About episodes. So why the extremely harsh attitude towards Dunning? He was wrong, so converse with him, don’t treat him like he clearly wrote the episode intending to mislead. At first glance this discourse is moving away from rational debate into ideological territory.

    Am I missing something?

  5. oh with such an important subject, and people using him as a source for “why DDT is ok and Rachel Carson is an idiot” it must be better to update pronto. I had three people use his work to shoot down my defense of Carson’s book.

    There is another well known skeptic that has had much controversy recently that has been adament that DDT will save endless lives in Africa and Carson is an idiot. He did a happy dance when the Dunning thing came out, and will I’m sure continue to defend to the end his prejudice without enough evidence on this subject.

    My only real objection is if people are using this to promote a “I haven’t read the book view and don’t have all my fact straight”…maybe a quicker update is called upon. Plus it would make the chat room where I hang out a lot more fun.

  6. kittynh,
    I see your point.

    But Dunning never said the phrases that “DDT will save endless lives” or that “Carson is an idiot”

    That’s the stuff I have a problem with. All else is fine by me.

  7. And, oddly enough, I didn’t use those phrases either.

    Dunning also said in his little disclaimer box: “The errors that have been pointed out to me so far are not, in my opinion, significant enough to alter my conclusions. I welcome any and all such corrections.”

    Except…nearly everything he said was factually incorrect, speaking as an entomologist and someone who’s spent time with this issue. That’s what I’m calling him out on. (Additionally, as of this writing none of my comments on Skeptoid have been approved.)

    I’m “harsh” on people that get stuff wrong when they should know better. Why should I pull my punches for Dunning? I’m sure ~I’ll~ be pummeled soon by some other skeptic as well :p

  8. bug_girl,
    I don’t disagree. I think I’m dangerously close to the skeptical debate of “tone”. But I think it’s worth pointing out. You did say this:

    “Each system is different, and that is why blanket statements that portray DDT as a panacea for solving malaria problems are false and, frankly, stupid.”

    I don’t see anywhere that Dunning made a blanket statement that DDT is a panacea for solving malaria problems. He was pretty measured in saying that it is a complex issue.

    Again, I guess he still got a lot of facts wrong that open him up to fair criticism. I just don’t like strawman type statements.

    In conclusion, for myself, I am disappointed in Dunning at this moment and I hope he surprises me with his correction episode.

  9. I think the response to Dunning’s podcast has been pretty ridiculous. First people assume without verifying that he was using “” as a source (he wasn’t). Then everyone is “shocked” by his conclusion of: we’re prolly using DDT the way we should except for Africa where maybe we should re-evaluate.

    Sounds pretty reasonable in the end to me, even if he got a few facts wrong in the post. Instead of engaging with Dunning, people attacked him, because he wouldn’t change his overall opinion (which isn’t that different than the consensus anyway).

    Beware the next skeptic who comes to a different opinion than the norm.

  10. @ShanePB: I haven’t seen anyone who has been upset about the conclusion he drew at the end of the podcast. People are upset that many of the facts in the middle of the podcast are just down right wrong and (whether Brian realizes it or not) the source for these facts is a known propagandist. The fact that he thinks Silent Spring was about eggshell thinning and that brown pelicans were killed by Newcastle disease shows that he didn’t look into the issue deep enough.

  11. I agree with Spaceguy87, by invoking more extreme examples of ‘manufactroversy’ at the start of this post (“Teach the Controversy!” “Global Warming is a hoax!” “Vaccines are poison!”), you do appear to be a lot harsher on Brian Dunning than his podcast warrants. His factual inaccuracies (of which I know nothing) should be (and probably will be) addressed. Does Dunning not just advocate the removal of purely ideological funding blocks of DDT? is that not just sensible?

  12. Clearly I failed to distinguish in my writing between the larger group of DDT boosters (I don’t know what to call them?) and Dunning.

    It’s a huge issue online–junkscience and sites of it’s ilk are at the top of Google’s results. But the loudest voices are not always the correct ones.

    I wanted to look at why Dunning got suckered by people who are advocating stupid stuff. He did use Junkscience as a source, since his factual errors are pretty much identical to their factual errors.

  13. Bug Girl,

    Thanks for the links and the information. I had a gut reaction that the DDT episode was wrong but I am not nearly well educated enough on the topic. I will read up on what you have posted. This particular episode had the feeling of a liberterian based as opposed to science based conclusion but I just don’t know enough.

    Thanks again.

  14. Bug Girl,

    I hope that my last post wasn’t too critical as pointing out the inaccuracies of something within your field of expertise is much appreciated. I hope Brian Dunning lives up to his billing by commenting on the concerns people have about that episode.

  15. Bug Girl –
    I don’t think you failed to get the message across at all. To me this was was such a large error on Dunnings part it needs to be pointed out without pulling punches.
    It certainly did cross my mind that someone like Dunning who pulls together a podcast every week is bound to make a few errors but it is his response to being corrected that has me most concerned. I simply do not see how he could have read the relevant information here, on Deltoid’s blog, and the copious links all have provided him and still say
    “The errors that have been pointed out to me so far are not, in my opinion, significant enough to alter my conclusions. I welcome any and all such corrections.”
    Uh…almost every goddamn factoid he presents was straight out of the classic misinformation campaign.
    To those defending Dunning: how do you account for his response to being shown just how badly he screwed up?
    Maybe it just burns me more as a forest entomologist.

  16. @bug_girl:

    DDT does have its place, and its current usage is probably not too far off of what it should be. The exception is Africa where DDT’s upside far outweighs the down, and my opinion is that donors should relax their restrictions against it, and leave those decisions to the experts on the front lines in Africa. For much of the rest of the world, DDT has largely been supplanted by newer and better agricultural pesticides, and there’s insufficient reason to put collateral species under pressure. A scientific review nearly always produces better focused policy, and our DDT policy is definitely due for a tuneup. ~Dunning

    With regard to human population risk, ongoing harm, and the mortality concerns associated with malaria in Africa, could you address the substance of Dunning’s conclusion; setting aside for a moment the dimly lit road he seems to have travelled on to get there?

  17. I think the response to Dunning’s podcast has been pretty ridiculous. First people assume without verifying that he was using “” as a source (he wasn’t).

    As Buggirl said (and also over at Deltoid), the mistakes he made came from, so it is reasonable to assume he got them there.
    The second reason he is getting so much criticism is rather than saying “yes, I didn’t read the book and I accepted the biased interpretations of other sources rather than directly checking them” He said “It’s irrational to criticise using a source just because you don’t like their political beliefs”

  18. @TimLambert: Thanks for that link. The policy statement seems reasoned and thorough which begs the question; why would Dunning jump into clear waters unless it was his intent to murky them up? Or perhaps Dunning thought there was a legitimate controversy or irrational beliefs that were restricting disease control efforts. It’ll be interesting to see if he provides a more thorough response.

  19. Beware the next skeptic who comes to a different opinion than the norm.

    well yah I have to agree with that. Because when something is not the norm of what other skeptics and scientists are saying, it’s really worth a good hard look.

    Dunning needs to really come clean on his mistakes. It doesn’t matter if he feels his conclusion is the same. When it comes to critical thinking, and in this case science, little mistakes aren’t kosher. Sloppy science is no science. I think it’s nice people are all “well I know Dunning will probably correct this…” but we don’t know until he does it. Meanwhile it stands as is with the errors. The nice thing about the internet is we don’t have to recall the book…it’s very EASY and fast to fix something or to admit a mistake (it happens!). In the day of the internet, we shouldn’t have to “wait and see”.

  20. I don’t know. It seems like some people have done enough for the skeptical movement to earn the benefit of the doubt.

    I’ll just check Mr. Dunning’s Twitter for an explanation…

    “That person just got up on the nasty side of bed, apparently. If anyone sends me a legit correction I’m always happy to use it.”

    Hm. Well, I guess he’s just an asshole.

  21. So here’s the big question in my mind…will Rebecca still appear with Brian in Melbourne? Will she pretend nothing is happening or will she be honest and public call him out on it?

    It would seem that this episode casts doubt on everything he’s done, and I no longer trust anything he puts out. I doubt I’ll even support the Skeptologists if he’s doing any of the writing for it.

    Very very sad…we lose Bill Nye to greed and now Dunning to dishonesty.

  22. Just to be clear–Rebecca and I are not the same person :)

    I do know that several people plan to ask Dunning some hard questions about the DDT issue when he’s in Australia.
    (and thanks so much Tim for answering some of the questions here while I’m traveling!!)

  23. @JOHNEA13: No, lack of pirates has caused global warming which in turn has caused autism rates to rise. I’ve seen a graph which proves it. (Don’t have the link handy, so you’ll just have to trust my authority.)

  24. Dunning: “The errors that have been pointed out to me so far are not, in my opinion, significant enough to alter my conclusions.”

    I guess for some people, the conclusions they reach are more important than the methods they use to get there. Which is all fine and dandy, I suppose – but critical thinking it ain’t.

  25. @bug_girl: All comments on are approved by default, they should appear immediately when they’re posted. It’s very rare that a moderator goes back and rejects one, and disagreeing with Brian has never been a criteria for that. There is no conspiracy of censorship against you. If you suspect a technical error, you’re as welcome to contact me or one of the moderators as anyone else.

  26. Hi Brian. Thanks for showing up. I didn’t actually posit a “conspiracy”; I just mentioned that my comments didn’t show up.
    I am looking forward to reading the post you have promised this Thursday.

    I also want to say how happy I am that I was wrong in my post; for the most part we didn’t get the usual DDT trolls. (A few did show up at my blog, but I have them on permanent moderation)

    I really hope this is a sign that the discussion can progress past “DDT Good/DDT Evil!” which is where it’s been stuck for a couple of years.

    1. It is odd watching a Skeptic say that junkscience is not a skeptical site, that we should follow the money. There is some money coming in from conservative sources, but probably gets as much money from Big Oil, Big Smoke, Big [fill in yours] as Brian does. Maybe a little more. I think Brian maybe donating more money to all of them than they are to him (although I didn’t seem him smoke).

      Junkscience position on DDT isn’t exactly set in stone. It isn’t all encompassing. All it really says is that the decisions made to ban it weren’t made due to science. They were made because of feelings.

      There is a lot of junkscience these days. You can’t open a paper and not find a study of some kind being reported. New terrors every week. All of them are junk. All of them are junk for a very simple reason, they look at the wrong end of the spectrum. There is a statistical lesson we all receive in Stats. “What is the chance that you will roll at least one 6 in 5 rolls of the dice?” The answer is of course 1 – 5/6^5. The epidemiologists have forgotten this silly little lesson.

      If you use the above lesson with smoking and lung cancer (the deadliest aspect of the hated habit), you discover that 92% of all smokers who start at age 15 and smoke till their 75 NEVER GET lung cancer. This is the result of a RR of 25. If you look at any other of the nasties that the epidemiologists have discovered, they result in 99.999% survival rates for those who partake of the sinful item.

      Junkscience showed me the way toward rational analysis. is not as good a site as it used to be. The money train was never really there.

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