DDT is a safe and effective pesticide. Banning it is an irrational, economy-damaging overreaction.

On the morning of June 14, 1972, William Ruckelshaus, the administrator of the newly created Environmental Protection Agency, issued his final order canceling the registrations of products containing DDT for most uses in the United States. The chemical industry, which had spent two years fighting the ban through formal EPA hearings, moved immediately to contest the decision. Press releases went out to newspapers. Industry spokesmen appeared on radio. The language of the counterattack was consistent and carefully prepared: DDT was safe, the evidence against it was exaggerated, and the ban was an ideologically driven overreaction that would cost farmers hundreds of millions of dollars and allow disease-carrying insects to flourish unchecked.

The timing mattered. Students who graduated from American high schools in June 1972 had spent years in classrooms where DDT was presented, at best, ambiguously. The pesticide had been in use since the 1940s, credited with major reductions in malaria, typhus, and other insect-borne diseases. During World War II, it had been dusted on soldiers and civilians by military health teams as a matter of standard procedure. Postwar agricultural promotion had treated it as one of the century's great scientific achievements. Health curricula had absorbed this history without the revision that accumulating scientific evidence demanded.

That evidence had been building for a decade before Ruckelshaus signed his order. Rachel Carson's Silent Spring, published in September 1962, had synthesized the available science on DDT's behavior in ecosystems: how it persisted in soil and water, how it concentrated as it moved up the food chain through a process called bioaccumulation, how it appeared in the fatty tissues of birds, fish, and mammals far from any application site. Peregrine falcon populations had collapsed. Bald eagle reproduction had dropped sharply. The mechanism was chemical, DDT interfered with calcium metabolism in birds, causing eggshells to thin to the point where incubating parents crushed their own eggs.

For humans, the picture was complicated in ways the industry successfully exploited. The carcinogenicity of DDT was not demonstrated with the same directness as its ecological harms. Animal studies had shown liver tumors in rodents exposed to high doses, but translating this to human risk required inferences that opponents of the ban attacked as speculative. The EPA hearings that ran from 1971 through early 1972 produced more than nine thousand pages of testimony, with industry scientists and academic allies arguing that the human health evidence was insufficient to justify prohibition.

Ruckelshaus reviewed the record and concluded otherwise. His opinion and order found that DDT was a probable human carcinogen, that it persisted in the environment far longer than had been acknowledged at the time of its introduction, and that its benefits for most domestic agricultural uses could be achieved with less persistent alternatives. He allowed a narrow exception for public health emergency use in controlling disease-carrying insects, an acknowledgment that the anti-malaria application remained a legitimate claim.

The industry's response shaped what graduates of 1972 took into adulthood. The ban was real, but so was the sustained campaign to characterize it as scientifically unsound. By the late 1970s, DDT's toxicological profile had been sufficiently established, and the populations of raptors had recovered sufficiently, that the grounds for ambiguity in health education had largely dissolved. But students who left classrooms in June 1972 had heard both sides presented as if equally grounded in evidence, at a moment when the evidence had already decisively shifted.