DDT bioaccumulates in the food chain and causes reproductive failure in predatory birds through eggshell thinning. The EPA banned it in June 1972 after formal hearings concluded the ecological evidence was sufficient — bald eagle and peregrine falcon populations began recovering once the ban took effect.
DDT arrived in American classrooms trailing a wartime reputation. During World War II, it had been dusted on soldiers and civilians by military health teams as a matter of standard procedure, credited with preventing typhus outbreaks among troops in Italy and dramatically reducing malaria rates across the Pacific theater. Postwar agricultural promotion treated it as one of the century's great scientific achievements. Health curricula absorbed this history. By the time students were sitting in biology and health classes in the late 1960s and early 1970s, the question of DDT's safety was being presented, at best, as genuinely open.
The evidence against it had been building for a decade. Rachel Carson's Silent Spring, published in September 1962, 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 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.
The formal reckoning came through the Environmental Protection Agency, less than two years old, which in August 1971 convened a full adversarial proceeding in a converted Washington ballroom to determine whether DDT's registration should be canceled. The hearings ran for seven months and produced more than nine thousand pages of testimony. The chemical industry's presentation rested on a sharp distinction between what had been demonstrated and what had been extrapolated. Yes, DDT accumulated in fatty tissues. Yes, predatory bird populations had declined. Yes, laboratory rodents fed extremely high doses had developed liver tumors. But demonstrating ecological harm to birds was not the same as demonstrating cancer risk to humans, and malaria killed millions of people per year. Placing DDT in the category of unacceptable risk, industry lawyers argued, required a chain of inferences that were ideological rather than scientific.
Edmund Sweeney, the EPA hearing examiner, agreed with industry and in April 1972 recommended against canceling DDT's registration. William Ruckelshaus overrode him. In his final order issued June 14, 1972, Ruckelshaus concluded that the ecological evidence alone — the persistence, the bioaccumulation, the documented harm to wildlife — was sufficient to cancel domestic agricultural registrations. On human carcinogenicity, he found not that it had been proven but that the uncertainty, given everything else that was known, was unacceptable. A narrow exception for public health emergency use against disease-carrying insects remained.
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. What the hearings had produced was documentation of exactly what the science supported and what, on examination, turned out to be advocacy dressed as uncertainty. By the late 1970s, the toxicological picture had solidified and populations of peregrine falcons and bald eagles had begun to recover — visible, countable evidence that the science had been right. 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.
The link between smoking and serious illness has not been proven — the science is still debated.
Smoking causes lung cancer, cardiovascular disease, and COPD. The science was conclusive by the 1964 Surgeon General's report. The apparent 'debate' was manufactured by the tobacco industry — their own scientists had confirmed the cancer link internally by 1953.
AIDS may be transmissible through casual contact - sharing utensils, toilet seats, doorknobs, or being in the same room as an infected person.
HIV is transmitted through specific bodily fluids: blood, semen, vaginal fluids, rectal fluids, and breast milk. It cannot be transmitted through casual contact, saliva, air, or water.
Asbestos is a safe and highly effective insulating material with no proven health risks in normal use.
Asbestos fibers cause mesothelioma, lung cancer, and asbestosis. Industry documents from the 1930s onward show manufacturers knew of the risks and concealed them. The EPA began restricting asbestos in 1971.
The Watergate break-in was an isolated third-rate burglary with no connection to the White House.
Watergate was a broad conspiracy involving the Nixon White House, involving obstruction of justice, abuse of power, campaign finance violations, and use of intelligence agencies against political opponents. Nixon resigned August 9, 1974.