Ken Parish gives a generally approving link to a piece of junk science claiming that bans on DDT inspired by Rachel Carson’s Silent Spring have caused the deaths of millions of third world residents. He also gives a link to a more balanced piece which gives cautious support to limited use of DDT in anti-malaria campaigns in poor countries (the only use that is currently legal, although there is widespread illegal use as an agricultural insecticide). While noting that not all of Carson’s 1962 claims about the dangers of DDT have stood up to subsequent scrutiny, the author dismisses right-wing conspiracy theories like those in the first link, and makes the point that Carson was campaigning against the use of DDT as a broad-spectrum insecticide, not as an anti-malarial. As the author notes

Soaking the biota in DDT like it was bubble bath, standard practice at the time Silent Spring was written, was a bad thing and Carson was right to condemn it.

As this piece makes clear, the main reason for the abandonment of DDT as the core component in anti-malaria campaigns was the growth of resistance, which was of course exacerbated by indiscriminate use. The ban on DDT use in developed countries, to the extent it had any effect, slowed the general rise of resistant species, and therefore increased the effectiveness of DDT in its anti-malarial use.

The main advantage of DDT is that it is cheap and persistent. Persistence is also one of the main disadvantages, along with broad-spectrum effects. For poor countries, and for the specific purpose of anti-malaria campaigns, the benefits arguably outweigh the costs, and this is why DDT continues to be used in these countries.

The question of when the extra cost of alternative pesticides is sufficiently small to justify abandoning DDT, or sufficiently large to justify readopting it in countries that have abandoned it, is an important one that needs careful analysis. The cause of rational debate is not assisted by propaganda pieces like the one Ken cited.

Note This version has been edited in response to points made by Ken in the comments thread.

5 thoughts on “DDT

  1. John,

    My link to the first article wasn’t “uncritical”, in that I put a more balanced article immediately underneath, and expressly noted that it was more balanced. The points you make are nevertheless useful to put the issue into perspective. However, some acknowledgment that Carson DID drastically beat up and massively exaggerate the facts in the interest of an effective scare campaign would have assisted in the balance of your own post.

  2. Yep, Ken’s right – your basic point may be fair ’nuff, but saying “not all of Carson’s 1962 claims about the dangers of DDT have stood up to subsequent scrutiny” misleads by understatement – saying “Carson’s book was full of deliberate distortions designed to exploit public ignorance and scare people” is nearer the mark.

    Its important because the political success of her strategy encouraged many Greens to continue alarmist tactics where the science is either used or ignored as convenient (look at the GMO ‘debate’), perhaps with ultimately counterproductive consequences.

  3. Oh, and another thing – no economist should accept at face value the assertion that “Soaking the biota in DDT like it was bubble bath [was] standard practice at the time Silent Spring was written”. Farmers have never used more insecticide than they need for the very good reason that the stuff costs. They do, and did, make fairly good calculations as to the economically optimum amount to use (although, of course, this cost/benefit calculation does not always include the public costs of incidental environmental damage)

  4. DD, I accurately summarised the piece Ken linked to [by Cecil Adams] If you disagree with this piece, which seemed pretty balanced to me, maybe you should take it up with the author, or with Ken.

    On the ‘bubble bath’ point I think I made it pretty clear that the reason DDT was overused was because no-one took account of the externalities (both environmental damage and resistance buildup).

    Both you and Ken assert that Carson deliberately distorted the facts. The only source I can find for this is a critique by Dr. J. Gordon Edwards which consists primarily of quibbles amplifed by vitriol (the words ‘vicious’, ‘despicable’ etc occurring in almost every paragraph). Do you have a more credible basis than this for your claim?

  5. “Do you have a more credible basis than this for your claim?”

    Only memories of how annoyed and disappointed I was when I first read the book in the mid 1970’s, despite then being quite ideologically sympathetic (another child of the 60s radicalised by Vietnam).

    I read it because there was renewed debate at the time about the impact of organochlorines on avian reproduction (they can interfere with calcium metabolism and might make eggshells thinner, although it turned out that you need an awful lot in the environment to hurt even top predators like eagles). I had almost finished a biochemistry major and was therefore in a reasonable position to do some reality checking.

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