DDT was falling out of favor even before the 1962 publication of ''Silent Spring,'' Rachel Carson's book that described the dumping of DDT and other pesticides on American towns and farms and detailed the destruction they caused. DDT had not been sold as a way to control malaria but to eradicate it, so the world would never have to think about malaria again. But eradication failed -- it is now considered biologically impossible -- and because DDT had not lived up to its billing, disillusion set in. At the same time, DDT's indiscriminate use was provoking the development of resistance among mosquitoes, and many countries were shifting to decentralized health systems, which meant they were no longer able to organize nationwide house spraying.

The move away from DDT in the 60's and 70's led to a resurgence of malaria in various countries -- Sri Lanka, Madagascar, Swaziland, South Africa and Belize, to cite a few; those countries that then returned to DDT saw their epidemics controlled. In Mexico in the 1980's, malaria cases rose and fell with the quantity of DDT sprayed. Donald Roberts, a professor at the Uniformed Services University of the Health Sciences in Bethesda, Md., has argued that when Latin America stopped using DDT in the 1980's, malaria immediately rose, leading to more than a million extra cases a year. The one country that continued to beat malaria was Ecuador, the one country that kept using DDT.

In the few countries where it is used today, DDT is no longer sprayed from airplanes, and no country admits to using it as an insecticide for crops -- although there are probably cases where it is diverted for agricultural use. Its only legitimate use is inside houses. Roberts said that the quantities used for house spraying are so small that Guyana, to take one example, could protect every single citizen of its malarious zones with the same amount of DDT once used to spray 1,000 acres of cotton. ''The negative environmental effects of DDT use that led to its banning were due to massive, widespread agricultural use,'' says a fact sheet published by Usaid (no fan of the chemical). ''Spraying limited amounts of DDT inside houses is considered unlikely to have major negative environmental impact.''

What about DDT's impact on the people inside the houses? The most serious evidence of DDT's harm to humans are a few studies showing that higher levels of DDE (the form DDT takes when it metabolizes) in a mother's blood is associated with premature birth and shorter duration of breast-feeding. But other studies have found no such associations. There was suspicion that DDT causes breast cancer, but study after study has found no connection. In general, DDT is feared for its effect on the environment, not on humans. It has been used on such a huge scale over the last 50 years that it is reasonable to think that if it had any serious effect on human health, we would know it by now.

Rereading ''Silent Spring,'' I was again impressed by the book's many virtues. It was serialized in The New Yorker in June 1962 and published in book form that September -- a time when Americans were living in the golden glow of postwar progress and science was revered. ''Silent Spring'' for the first time caused Americans to question the scientists and officials who had been assuring them that no harm would result from the rain of pesticides falling on their farms, parks and backyards. Carson detailed how DDT travels up the food chain in greater and greater concentrations, how robins died when they ate earthworms exposed to DDT, how DDT doomed eagle young to an early death, how salmon died because DDT had killed the stream insects they ate, how fiddler crabs collapsed in convulsions in tidal marshes sprayed with DDT.

''Silent Spring'' changed the relationship many Americans had with their government and introduced the concept of ecology and the interconnectedness of systems into the national debate. Rachel Carson started the environmental movement. Few books have done more to change the world.

But this time around, I was also struck by something that did not occur to me when I first read the book in the early 1980's. In her 297 pages, Rachel Carson never mentioned the fact that by the time she was writing, DDT was responsible for saving tens of millions of lives, perhaps hundreds of millions.

DDT killed bald eagles because of its persistence in the environment. ''Silent Spring'' is now killing African children because of its persistence in the public mind. Public opinion is so firm on DDT that even officials who know it can be employed safely dare not recommend its use. ''The significant issue is whether or not it can be used even in ways that are probably not causing environmental, animal or human damage when there is a general feeling by the public and environmental community that this is a nasty product,'' said David Brandling-Bennett, the former deputy director of P.A.H.O. Anne Peterson, the Usaid official, explained that part of the reason her agency doesn't finance DDT is that doing so would require a battle for public opinion. ''You'd have to explain to everybody why this is really O.K. and safe every time you do it,'' she said -- so you go with the alternative that everyone is comfortable with.

''Why it can't be dealt with rationally, as you'd deal with any other insecticide, I don't know,'' said Janet Hemingway, director of the Liverpool School of Tropical Medicine. ''People get upset about DDT and merrily go and recommend an insecticide that is much more toxic.''

Because the ban on DDT became the midwife to the environmental movement, the debate about it, even today, is bizarrely polarized. Most environmental groups don't object to DDT where it is used appropriately and is necessary to fight malaria. But liberals still tend to consider it a symbol of the Frankenstein effects of unbridled faith in technology. For conservatives, whose Web sites foam at the mouth about the hypocrisy of environmentalists, DDT continues to represent the victory of overzealous regulators and Luddites who misread and distort science.

So far, conservatives have not been able to budge Usaid, even though they have managed to remake the agency's overseas AIDS programs to promote abstinence and discredit condom use. But malaria is not part of the public debate as AIDS is, and DDT does not have the same cultural urgency for the religious right that abstinence does.

William Ruckelshaus, the head of the newly created Environmental Protection Agency, banned DDT in 1972. It remains one of the most controversial decisions the E.P.A. has ever taken. Ruckelshaus was under a storm of pressure to ban DDT. But Judge Edmund Sweeney, who ran the E.P.A.'s hearings on DDT, concluded that DDT was not hazardous to humans and could be used in ways that did not harm wildlife. Ruckelshaus banned it anyway, for all but emergencies.

Ruckelshaus made the right decision -- for the United States. At the time, DDT was mainly sprayed on crops, mostly cotton, a use far riskier than indoor house spraying. There was no malaria in the United States -- in part thanks to DDT -- so there were no public health benefits from its use. ''But if I were a decision maker in Sri Lanka, where the benefits from use outweigh the risks, I would decide differently,'' Ruckleshaus told me recently. ''It's not up to us to balance risks and benefits for other people. There's arrogance in the idea that everybody's going to do what we do. We're not making these decisions for the rest of the world, are we?''

In fact, we are -- the central reason that African nations who need DDT do not use it today. Washington is the major donor to W.H.O. and Roll Back Malaria, and most of the rest of the financing for those groups comes from Europe, where DDT is also banned. There is no law that says if America cannot use DDT then neither can Mozambique, but that's how it works. The ban in America and other wealthy countries has, first of all, turned poor nations' agricultural sectors against DDT for economic reasons. A shipment of Zimbabwean tobacco, for example, was blocked from entering the United States market because it contained traces of DDT, turning Zimbabwe's powerful tobacco farmers into an effective anti-DDT lobby. From a health point of view, of course, American outrage would have been more appropriate if traces of tobacco had been found in their DDT than the other way around.

Then there are chemical companies. ''I get asked all the time -- are you being paid by chemical companies?'' said Thomas DeGregori, a professor of economics at the University of Houston and an advocate for DDT. The question is amusing, because the corporate interests in this issue are actually on the other side. DDT is no longer on patent, and it is known to be made only in India and China -- and the price has soared since the rich-country ban put manufacturers out of business, making it harder for poor countries to buy. Janet Hemingway of the Liverpool School, who advises African governments, said that she and the officials she works with are often lobbied by chemical companies selling more expensive insecticides, telling her about DDT's evils. ''Clearly, they'd like to see DDT banned -- it cuts into their markets,'' she said.

The only kind of liberalism I feel is worth defending is one that when conditions change, it changes its response to reflect the new circumstances. If Rosenberg is correct that inside the house spraying of DDT can make a tremendous difference in mosquito control and malaria suppression, and that there is little or no danger to humans or animals from spraying in such amounts, then it's really incumbent upon us to support programs which fund that spraying through Western aid institutions.

Take a look at the entire article and make up your own mind. It's available here and, as a PDF, here.