War on science: Spinning DDT, slandering the dead


What rational person would have thought irrationality could be in such surplus?

My post on the silly opposition to naming a post office after Rachel Carson produced a minor response. Reader Electratig took me to task at his blog.

Criticism is based on interesting claims that millions have died unnecessarily because the entire planet was driven to ban DDT, which is really not toxic to humans, and which really is the panacea that would rid the world of malaria. I’m surprised that DDT isn’t implicated as a cure for the designated hitter rule, too. The criticisms don’t hold so much water as the critics claim, I find.

A commenter, Fred, said, for example:

Actually, one can also go to the Library of Congress and find that Dr. Paul Muller won the Nobel Prize in 1948 for perfecting the chemical compound now known as DDT. One can also go to the Library of Congress and find that the National Academy of Sciences attributed DDT to saving 500 million lives. One can also find in the Library of Congress the World Health Organization’s affirmation that no substance has ever proved more beneficial to man than DDT. One can also find there that famous environmentalist, J. Gordon Edwards swallowed a tablespoon of DDT on stage before every lecture on the subject, living to age 84 when he died of a heart attack while climbing Divide Mountain at Glacier National Park.

Again, there is additional information available in the Library of Congress showing Rachael Carson’s quoting of scientific studies, such as that of Dr. James DeWitt, was very selective and misrepresented the actual data obtained by DeWitt. Later studies have shown that factors other than DDT caused of the decline of eagles and certain other birds in the DDT era. In fact, there were great increases in mammals and game birds during the DDT era. For example, observers spotted 12 times more robins in the DDT era than before.

Apart from my feeling that anyone who took a tablespoon of DDT before every public appearance is too crazy to be subject to the chemical, I haven’t found any corroborating information. But one must wonder: Malaria now kills about a million people a year; how many years would DDT have to be used to save 500 million lives?

Fortunately DDT has not proven to be a potent human carcinogen. I had not recalled that Carson even discussed carcinogenicity in Silent Spring, but other references make it clear she did. That is the high water mark of the case for DDT, and for the case against Carson.

There is much more research to be done, but the problems in the case against Carson and against a DDT ban suffer from classic symptoms of bogus science and bogus and voodoo history. Here are some of the problems.

First, there is no absolute ban on DDT. The chemical is still manufactured by U.S. companies — perhaps not on U.S. soil, I’m not sure. There are a few cases where a near-nuclear bomb option is needed, and DDT is available for that. Were DDT the panacea critics claim it is, there would be serious pressure to use it.

Second, DDT’s effectiveness against malaria-carrying vectors is not so great as the critics claim This is an area where one begins to think the critics are all creationists. DDT’s effects in driving mosquito evolution by selection were well-known and carefully and adequately documented when I studied biology in college, more than three decades ago. For one quick example, originally DDT was sprayed on walls of homes in villages where malaria posed a threat. Mosquitoes tended to bite victims, then fly to the nearest wall to rest before moving on. If the wall had DDT on it, since DDT is a contact poison, the mosquito would die. Anyone familiar with natural selection in evolution can see this one coming miles away: Within a few months, mosquitoes in these villages no longer made the stop on the walls on the way out of a house after biting victims. The instinct to do so had been selected out, or rather, the instinct not to stop in the habitation had been selected for, artificially, by the DDT. To continue DDT’s effectiveness, much more area would have to be sprayed than was economically feasible.

However, there was a more pernicious change brought about. Mosquitoes developed a gene that allowed them to digest the poison, rather than die from it. DNA studies show that this gene did not exist in any substantial form — perhaps not at all — prior to DDT spraying. Today, however, most mosquitoes carry multiple copies of the gene. DDT simply will not kill these mosquitoes. (This case is discussed in Jonathan Weiner’s book, The Beak of the Finch, A Story of Evolution in Our Time, which won a Pulitzer for general non-fiction in 1995.)

Also, the World Health Organization notes in its discussions of malaria that many nations simply did not have the wherewithal to mount an effective DDT spraying campaign. Reasons are many, but they include the fact that such spraying proved to have other unintended and undesirable effects, especially on birds and fish.

Third, research does not show that DDT is perfectly safe, nor that it is NOT a human carcinogen. Research shows DDT to be a carcinogen for mammals; no specific connection has been found to breast cancer in humans, but there are other cancers that may be caused. Perhaps more critically, the other, non-cancer health effects are bad enough. Any toxin will tend to cause liver damage. DDT is linked to liver damage in humans, though not strongly.

Fourth, the claims of the critics are fantastic. 500 million lives saved by DDT? I cannot find any corroboration of such a claim. If we assumed that malaria would have killed 10 million people a year between 1950 and 2000, the figure might be accurate. But malaria mortality has been well below that level for a long time, mostly without DDT. WHO itself makes no claims at all for DDT (see page 12 of the .pdf, the Executive Summary).

Fifth, WHO determined that more lives could be saved if the focus of the campaign changed from the impossible goal of total eradication of mosquitoes, to the more rational goal of improving prevention efforts and boosting health care in third-world nations to save lives of people affected. Spraying DDT is impressive, but DDT is not pixie dust. Using mosquito netting often provides a better short-term and long-term solution, without a full-scale attack on the environment. When the health-care professionals decide a different tactic would be more effective, it seems silly and dishonest to blame a ban on DDT. The Roll Back Malaria campaign discusses the negotiations on the treaty that limits DDT:

RBM’s objectives throughout this process were:

to establish consensus on the present and future role of DDT and alternatives in malaria control;
to encourage greater involvement of public health specialists in country-level discussions about the treaty and in country delegations to the negotiating sessions;
to provide information to negotiators and others that would reduce controversy and result in a win-win situation for public health and the environment (in which the longer term goal of DDT elimination is achieved through strengthened, more robust malaria control);
to benefit from the media attention to inform the public about malaria; and
to mobilize resources to support malaria control from outside the health sector.

All of these objectives have been met and the final treaty, known as the ‘Stockholm Convention on persistent Organic Pollutants’ provides for the continued public health use of DDT and international assistance for the development and implementation of alternatives.

Resources to support the initial work of the RBM Secretariat were provided by environmental agencies/offices. In addition, the Pan American Health Organization (PAHO) and the WHO Regional Office for the Americas (AMRO) and most recently the WHO Regional Office for Africa (AFRO) have been awarded project development grants from the Global Environment Facility (GEF) to promote regional efforts to strengthen malaria control and reduce reliance on DDT.

Sixth, the sources for the case against Carson and against the DDT limitations is suspect. Lyndon LaRouche? Is there anyone who takes seriously anything coming from that peculiar special interest any more? More critically, is there any ethical reason to urge LaRouche’s bizarre views on such an issue? I doubt it. (One wonders if the GOP 53 who voted against naming the post office for Rachel Carson realized they were carrying LaRouche’s water.) It’s difficult not to appear to be making a priori judgments on LaRouche’s statements, succumbing to a poisoning the well argument. But those of us who have had to deal with LaRouche for 30 or more years have come to understand that most of the claims made by the man and his organizations are bizarre, generally unsupportable by the facts, biased for odd political reasons — generally untrustworthy. I’ll require other sources, please. (This applies to the claims of J. Gordon Edwards — as far as I can tell, his views are promulgated solely by the LaRouche organization, without hard scientific corroboration.)

Seventh, the critics against Carson and the DDT ban fail to deal with the most serious issues. As DDT researcher Paul Muller detailed in his Nobel lecture (he won the Nobel in 1948 for his work studying and promoting DDT), the pesticide is incredibly long-lived. When DDT breaks down, it breaks down into DDE, among other things, another deadly, long-lived toxin. While this is an advantage in some situations, it drives mosquito evolution to contribute to the ineffectiveness of the poison, and it makes it a serious problem in ecosystems, where DDT is quickly concentrated in the tissues of primary, secondary, tertiary and quaternary consumers (insects, the things that eat insects and the plants sprayed with DDT, and the things that prey on insect and plant eaters).

Ending indiscriminate use of DDT has led to a dramatic recovery especially of raptors in riparian environments, osprey, golden and bald eagles especially. Whatever the specific cause of the thinning egg-shells that led to the decline of these animals, the reduction of DDT proved effective in fixing the problem. The long-term effects of DDT and its breakdown compounds is still highly controversial. Some of the by-products act as hormones, especially estrogen, and there are studies that indicate DDT and its daughter by-products still affect animals today, causing bizarre growth of reproductive organs especially, rendering creatures unable to reproduce.

The case against Rachel Carson is inflated and uncorroborated by science and history. For heaven’s sake, name the post office in her honor, and let’s get on to serious stuff.

2 Responses to War on science: Spinning DDT, slandering the dead

  1. EliRabett says:

    The original sin in science denialism is tobacco. Not surprisingly it also was the source of Rachel Carson kills zillions

    Like

  2. JimV says:

    I was suspicious of the claims (favoring DDT) in the previous thread. Thank you for taking the time to research them and respond.

    Like

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