In his novel, Adolf Hitler: My Part in His Downfall, Spike Milligan describes waiting for the train to take him to his first military posting during WWII. His commanding officer hands him a picture of Hitler labeled: This is your enemy. "I searched every compartment," writes Milligan, "but he wasn't on the train."
In a way, we are still searching for the Führer. Hitler is the archetypal enemy, whose badness virtually all can agree on, which is why his name often crops up in discussions about contemporary world leaders. Opponents of Saddam Hussein, Ariel Sharon, and Robert Mugabe have drawn comparisons between their respective nemeses and the Führer. It is a forceful, albeit lazy, way to clarify the muddy moral waters of modern international politics.
The same argumentative tactic is used in discussions surrounding other tricky issues. Since starring as the lead villain in Rachel Carson's seminal environmentalist text, Silent Spring, the insecticide DDT is to environmental destruction what Hitler is to murderous dictators. No surprise, then, when Zak Goldsmith, editor of The Ecologist magazine, uttered those three infamous consonants during a recent BBC radio discussion on nanotechnology. Stressing his case for a moratorium on nanotech research, Goldsmith said: "Scientists do make mistakes: Look at DDT." In other words, nanotech is as dangerous as that nasty synthetic chemical, which everybody knows kills birds and gives people cancer. Nothing more needs to be said. Let's have a moratorium.
However, while Hitler undoubtedly oversaw the murder of up to six million Jews, it is unclear what DDT actually did to earn its fearsome reputation. Indeed, DDT played a crucial part in the war against Hitler. In the Pacific arena, malaria was decimating Allied forces until DDT bombs were dropped to clear mosquitoes ahead of advancing troops.
Postwar, DDT hastened malaria's elimination from Europe and North America and proved highly effective against agricultural pests. These successes prompted the World Health Organization to launch the wildly ambitious Global Malaria Eradication Program in 1955. Despite saving tens of millions of lives and clearing malaria from large swaths of the world, the pesticide did not eradicate the disease: Mosquito populations quickly became resistant to DDT, proving too much for the DDT-dependent program. WHO abandoned the plan in the 1960s.
But this was a "mistake" only in that the eradication program was less successful than it might have been. "If one retrospectively supplants the unrealistic goal of eradication with one of control," wrote malariologist J. Kevin Baird, "the campaign appears brilliantly successful."1
The benefits reaped from liberal DDT use were not won without cost. DDT accumulated in food chains and interfered with the reproductive physiology of birds of prey, leading to the near extinction of such iconic species as the bald eagle and peregrine falcon. These problems led to its ban in agricultural use across the developed world--and the birds bounced back. In this respect, the DDT story becomes a lesson in how well society responds to problems arising from new technologies.
Although the US Environmental Protection Agency classified DDT as a probable carcinogen, based on high-dose animal tests, extrapolations to humans reveal that the carcinogenic risk posed by the average daily intake of DDT during the agricultural era was a 50th of that posed by the natural toxins in the coffee we drink, and half that from the celery we eat. In 1999, the US National Research Council reported no association between environmental DDT levels and human cancers. The only health problem associated with the comparatively tiny quantities of DDT used in antimalarial operations is a reduced duration of lactation in nursing mothers, but to a degree that has no measurable consequences on infant health. Any such downsides must be weighed against the undoubted benefits of DDT in controlling malaria, which still kills three million people annually, mostly children.
Although mosquito resistance to DDT scuppered the eradication program, it was not universal. In certain situations, DDT remains the best antimalarial measure available. In South Africa, the resumption of DDT spraying in 2000 brought malaria under control following a six-fold increase in infection rates caused by mosquitoes that had developed resistance to pyrethroid insecticides.
If scientists made a "mistake" with DDT, it is that they let it be snatched from their grasp by the force of erroneous popular opinion. Negative perceptions of DDT endured beyond the agricultural ban and soon impinged on public health applications. Many malaria- ridden countries scaled down or stopped DDT spraying, following pressure from Western aid organizations. DDT's continued effectiveness is further undermined by the lack of even an inventory of the mosquito populations that remain susceptible to it.2
Contrary to popular opinion, DDT is no Hitler. Goldsmith's comments reflect and reinforce these erroneous perceptions, which in turn contribute to the ongoing rise in malaria. They also contribute next to nothing to the nanotechnology debate. Like Spike Milligan, Goldsmith is clutching a picture of the enemy. The trouble is that Goldsmith's portrays the wrong man.
Stuart Blackman is a freelance science journalist in the UK.
1. J. Kevin Baird, "Resurgent malaria at the millennium: Control strategies in crisis," Drugs, 59:719-43, 2000.
2. R.S. Desowitz, Federal Bodysnatchers and the New Guinea Virus, New York: W.W. Norton & Co., 2002, p. 69.