Conservation Challenge: DDT

DDT raised possibility of a “Silent Spring” without birds

In 1962, Rachel Carson wrote her seminal book, “Silent Spring,” which alerted the world to the environmental dangers of DDT. Eventually, the use of the pesticide (dichlorodiphenyltrichloroethane) was banned in the United States and other countries.

The Peregrine Falcon was one of the species hit especially hard by the widespread use of DDT in the 1950s and ’60s. Subsequent research showed that DDT and its derivatives broke down very slowly in the environment, accumulated in the food chain (becoming more concentrated with each link), and reached such high levels in top predators, such as the Peregrine Falcon, that it interfered with their calcium metabolism and caused eggshell thinning in birds. By 1972, when DDT was banned, Peregrine Falcons were gone from the eastern half of the United States.

The Peregrine Fund was founded in 1970 to bring the falcon back from the brink of extinction through captive breeding and release to the wild. More information about our history is available here.

Birds of prey are excellent indicators of environmental health. Their problems are an early warning system that there may be effects on people, too. Recent studies have shown that childhood exposure to DDT and its derivatives from 1945 through the 1950s is linked to a five-fold increased risk of breast cancer in women who are now in their 50s.

In some parts of the world, use of DDT is once again being proposed to aid in control of malaria, which is carried by insects. Careful indoor use of DDT may be acceptable, but the lessons learned from a half-century ago need to be remembered today.

Projects necessitated by this challenge