DDT (dichloro diphenyl trichloroethane) was developed for the military as a powerful pesticide to protect soldiers in mosquito-ridden tropical climates. By the 1940’s, it was manufactured for civilian use and used in large quantities all over the world for eradicating disease-bearing and crop-killing insects. DDT saved millions of lives in malarial zones and saved millions from starvation. The creator of this miracle chemical, Paul Muller, won the Nobel Prize in Physiology or Medicine.
Yet in the 1950’s and 60’s, many began to notice alarming declines (almost to the point of extinction in some cases) in the populations of several predatory bird species, namely, the bald eagle, cormorant, osprey, brown pelican, and peregrine falcon. DDT was soon identified as the culprit. But DDT was not killing these species outright. Rather, the exposure to DDT affected the birds’ calcium levels, and caused them to produce thin-shelled eggs; shells too thin to support the developing embryos. Populations declined because young could not survive past their embryonic stages.
The book that changed everything
The fact that predatory bird species were declining was alarming to many in the United States. Scientists began studying the impact of DDT on the environment. In 1962 Rachel Carson, an American naturalist and author, wrote Silent Spring in which she described the harmful effects of DDT on the environment. She also accused chemical companies of spreading misinformation about the pesticides to the public and called out public officials for accepting industry claims without any evidence to support them.
Silent Spring brought environmental issues to the American public and is widely credited with launching the environmental movement. Carson was met with fiery opposition by the chemical companies, but her work initiated a changed in the national pesticide policy, a nationwide ban on DDT in 1972, and inspired the environmental movement that led to the creation of the Environmental Protection Agency.