DDT insecticide

DDT emerged because the compound had been synthesized in 1874—65 years before its insecticidal properties were recognized—waiting for someone to ask the right question. That question came from Paul Hermann Muller at J.R. Geigy in Basel, who sought a contact poison effective against insects but safe for mammals.

The molecule itself was ancient by 1939. Austrian pharmacologist Othmar Zeidler had first synthesized dichlorodiphenyltrichloroethane in 1874, but he was investigating compounds, not insecticides. The molecule sat in chemistry's archive, a solution awaiting its problem.

Muller joined Geigy in 1925 as a research chemist. By the late 1930s, Switzerland faced serious agricultural pest problems, and Muller began systematically testing compounds for insecticidal activity. After four years and 349 failures, in September 1939 he placed compound number 350 in his fly cage. The flies dropped and died. What distinguished DDT was not just lethality but persistence—a single application continued killing insects for months.

Geigy secured a Swiss patent in 1940, followed by UK (1942), US and Australian patents (1943). They marketed two DDT products: Gesarol spray insecticide (5% concentration) and Neocid dust (3%). But the true test came with war.

In January 1944, DDT quashed a typhus epidemic in Naples—the first time a winter typhus outbreak had ever been stopped. The disease was carried by lice; DDT destroyed the vector. Allied troops had their shirts impregnated with DDT throughout the Far East campaign, maintaining army health in tropical theaters where malaria had historically killed more soldiers than combat.

Muller received the 1948 Nobel Prize in Physiology or Medicine—remarkable given he was neither physician nor medical researcher. The prize recognized DDT's immense impact: between the 1950s and 1970s, it helped eradicate malaria from the United States and most of Southern Europe.

The story turned dark with Rachel Carson's Silent Spring in 1962. DDT's very persistence—its original advantage—meant bioaccumulation through food chains, thinning eggshells in raptors, poisoning ecosystems. The US EPA banned DDT in 1972. Today, limited use continues for malaria control in developing countries, but the compound that saved millions also demonstrated that every technological solution creates new problems.

Muller died in 1965, before the full environmental reckoning. He had seen his discovery transform public health; he did not live to see it become a cautionary tale about unintended consequences.