DDT

DDT—dichlorodiphenyltrichloroethane—illustrates how compounds can exist for decades before anyone discovers their transformative applications. In 1874, Othmar Zeidler, a doctoral student at the University of Strasbourg, synthesized the white crystalline powder as part of his thesis work on chlorinated hydrocarbons. He recorded the synthesis procedure, noted some physical properties, and moved on. The compound sat in chemistry journals for sixty-five years, a curiosity without a purpose.

The adjacent possible for DDT's discovery as an insecticide didn't open until the late 1930s. Paul Hermann Müller, a chemist at the Swiss company Geigy, was systematically testing compounds for insecticidal properties. The need was urgent: conventional insecticides like arsenic compounds were toxic to humans, and pyrethrum from chrysanthemums was expensive and supply-constrained. Müller tested hundreds of compounds before reaching DDT in September 1939. The results were extraordinary—the compound killed insects on contact and remained lethal for months after application.

World War II transformed DDT from a laboratory discovery into a global phenomenon. Allied forces dusted soldiers and civilians with DDT powder to control typhus-spreading lice. In Naples during the winter of 1943-1944, mass DDT applications stopped a typhus epidemic that had killed millions in previous wars. Malaria control programs sprayed DDT in homes and swamps across the Pacific and Mediterranean theaters. By war's end, DDT was credited with saving millions of lives. Müller received the Nobel Prize in Physiology or Medicine in 1948.

The postwar cascade seemed limitless. Agricultural applications promised to eliminate crop pests. Public health programs aimed to eradicate malaria globally. DDT was cheap, effective, and apparently safe—soldiers had been liberally dusted with it without obvious harm. The compound accumulated in soils and organisms, but this persistence was initially considered an advantage: one application protected for months.

The reckoning came slowly, then suddenly. Scientists observed that DDT concentrated as it moved up food chains—a process called bioaccumulation. Fish accumulated it from water; birds accumulated more from fish; raptors at the top of food chains accumulated lethal concentrations. By the 1960s, populations of bald eagles, peregrine falcons, and brown pelicans had collapsed. Rachel Carson's 'Silent Spring' in 1962 synthesized these findings into a devastating critique that launched the modern environmental movement.

The United States banned DDT for agricultural use in 1972. The compound persists in ecosystems decades after application ceased—its durability, once an asset, became its most damning property. Yet DDT's story resists simple moralization. The World Health Organization still recommends indoor DDT spraying for malaria control in endemic areas, where the disease kills hundreds of thousands annually. The compound that nearly drove the bald eagle to extinction continues to save lives where malaria remains endemic. DDT demonstrates that technologies can be simultaneously miraculous and catastrophic, depending on context, scale, and what we choose to measure.