This is the second in a series of Fisks of “100 things you should know about DDT,” a grotesquely misleading list of factoids about DDT put up a site called JunkScience.com. While one would assume that such a site would be opposed, this particular site promotes junk science. I’m not taking the points in order.The “100 things” list is attributed to Steven Milloy, a guy who used to argue that tobacco use isn’t harmful, and who has engaged in other hoaxes such as the bizarre and false claim that Compact Fluorescent Lightbulbs (CFLs) can pose serious toxic hazards in your home (and therefore, you should continue to waste energy with less efficient bulbs); and to J. Gordon Edwards, a San Jose State University entomologist who, despite being a great entomologist, was a bit of a nut on some political things; Edwards assisted Lyndon Larouche’s group in their campaign against Rachel Carson before his death in 2004. (Did Edwards actually have a role in the development of this list?)
100 things you should know about DDT
Claim #8. Some mosquitoes became “resistant” to DDT. “There is persuasive evidence that antimalarial operations did not produce mosquito resistance to DDT. That crime, and in a very real sense it was a crime, can be laid to the intemperate and inappropriate use of DDT by farmers, especially cotton growers. They used the insecticide at levels that would accelerate, if not actually induce, the selection of a resistant population of mosquitoes.”
[Desowitz, RS. 1992. Malaria Capers, W.W. Norton & Company]
Cover of The Malaria Capers, by Robert S. Desowitz
This was what Rachel Carson warned about. Indiscriminate use of DDT, such as broadcast application on crops to kill all insect, arthropod or other pests, would lead to mosquitoes and other dangerous insects developing resistance to the chemical. Of course, resistance developed as a result of overspraying of crops has exactly the same result, in the fight against malaria, as overuse in the fight against malaria. Cover of The Malaria Capers, by Robert S. Desowitz
Worse, such overuse also killed predators of mosquitoes, especially birds. In an integrated pest management program, or in a well-balanced ecosystem, birds and other insect predators would eliminate a large number of mosquitoes, holding the population in check and preventing the spread of malaria. Unfortunately, when the predators are killed off, the mosquitoes have a population explosion, spreading their range, and spreading the diseases they carry.
Assuming Milloy quoted the book accurately, and assuming the book actually exists, this point says nothing in particular in favor of DDT; but it reaffirms the case Rachel Carson made in her 1962 book, Silent Spring. Contrary to suggestions from the campaign against Rachel Carson, she urged that we limit use of DDT to tasks like preventing malaria, around humans, to preserve the effectiveness of DDT and prevent overspraying.
And then, there is this: Milloy doesn’t bother to quote the first part of the paragraph he quotes, on page 214 of Malaria Capers. Here is what the paragraph actually says:
There were a number of reasons for the failure, not least that the anophaline vector mosquitoes were becoming resistant to the action of DDT both physiologically — they developed the enzymes to detoxify the insecticide — and behaviorally — instead of feeding and wall-resting, they changed in character to feed and then quickly bugger off to the great outdoors. [from this point, Milloy quotes correctly]
In other words, the DDT-based campaign against malaria failed because DDT failed; mosquitoes became resistant to it. DDT’s declining ability to kill mosquitoes is one of the major reasons DDT use plunged after 1963, and continues to decline to no use at all.
To combat the dastardly campaign of calumny against Rachel Carson and science, you should also read: Deltoid, here, here and here, and the rest of his posts on the topic; Bug Girl, here, at least, and here, and the rest of her posts; denialism, here; and Rabett Run, here.