Jeffrey A. Lockwood is the author of Six-Legged Soldiers: Using Insects as Weapons of War, which is the first book to reveal systematically the biologically powerful, weirdly creative, and truly frightening ways in which insects have been, and may yet be, used as weapons of war. In the first of a three-part account of the bizarre and terrible linkage between insects and insecticides, he looks at synthesizing insecticide on a grand scale. Check back over the next two days to read more.
Fearful that the Allies were weaponizing the Colorado potato beetles, the Nazi high command charged German scientists with developing better, cheaper insecticides. Dr. Gerhard Schrader—one of the premier chemists working for one of the top firms, I.G. Farbenindustrie in Leuerkusen—took up the challenge. He started his investigations with organic (carbon-based) compounds to which he bound sulfur and fluorine—a reasonable beginning given the toxic properties of these additives. But Schrader had a hunch, the sort of vague intuition that bubbles up from a lifetime of scientific experience. He suspected that phosphorous, if properly placed on a skeleton of carbon atoms, could make for a very lethal molecule. Beginning in 1935, Schrader methodically synthesized an enormous series of organophosphorous compounds. The early products were not terribly toxic, but they showed enough promise to sustain the chemist’s curiosity into the following year. On the 23rd of December 1936, Schrader’s hunch paid off with an organophosphate that would change the world.
The good news was that this chemical functioned as an extraordinarily effective insecticide. When sprayed at a concentration of 5 parts per million (the equivalent of two teaspoons of liquid diluted into a typical hot tub), the compound killed 100 percent of the aphids on the test plants. Excited by these results, he began manufacturing trials in January. And then came the bad news.
Although synthesizing the insecticide at an industrial scale would not be difficult, keeping the plant workers alive would be a challenge. There were, what he tactfully termed “extremely unpleasant” side effects on humans. Absolutely dedicated to science, Schrader and his assistant had decided to test the chemical on themselves to ascertain its effects on people who might be exposed to it during factory production or agricultural application. “The first symptom noticed,” he later recalled, “was an inexplicable action causing the power of sight to be much weakened in artificial light. In the darkness of early January it was hardly possible to read by electric light, or after working hours to reach my home by car.” And it got worse. Even the slightest drop caused acute difficulty in breathing, and it was three weeks before the two men recovered from the effects of their self-inflicted study. During their convalescence, they came to accept that the chemical was too toxic to use as an insecticide, but they didn’t know how incredibly lucky they’d been. For Gerhard Schrader and his assistant had managed to survive the first ever human exposure to a brand new class of weapons, the world’s most lethal synthetic chemical—nerve gas.