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.