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17.7: Rachel Carson and DDT

In 1962, a former marine biologist for the U.S. Fish and Wildlife service, Rachel Carson, sent waves throughout both the scientific community and American society that would galvanize a country against the indiscriminate use of one of the most powerful pesticides available at the time. 

When it was developed during World War II, DDT was hailed as a miracle chemical. It could eliminate the hordes of malarial mosquitos in the South Pacific and quickly de-louse troops in Europe. It was so effective, that it's inventor was awarded a Nobel prize. When DDT was made available for civilian use in 1945, its application exploded into agriculture and became the gold-standard for pest control. However, DDT soon proved to be too effective in it's ability to kill.

DDT (dichlorodiphenyltrichloroethane) is a considered a "bioaccumulative and toxic chemical" by the EPA. It gained this designation because of the relatively long time it takes to degrade in the environment (15+ years!) and its ability to be stored in biological tissues. As it goes up the food chain, from plants to insects to birds and fish and eventually even to humans, DDT accumulates in the fat tissue of organisms exposed to it. This process is termed bioaccumulation or biomagnification, and can have serious impacts on the structure of ecological communities and the human health. According to the EPA, harmful effects of DDT on humans include (see the full EPA summary here):

  • Probable human carcinogen
  • Damages the liver
  • Temporarily damages the nervous system
  • Reduces reproductive success
  • Can cause liver cancer
  • Damages reproductive system

 

In her book Silent Spring, Rachel Carson presented the possible effects of DDT on animal and human populations. Her warnings about the devastating impacts of unregulated DDT use sent fear and outrage through the country and within 10 years, DDT had been banned in the United States.

DDT is still used in some parts of the world today, despite a wealth of research that shows its harmful effects. However, the legacy of Silent Spring is in the way it demonstrated to the world the capability of humans to drastically alter and damage the natural world. Carson's work has inspired thousands, and many credit her with founding the field of environmental science.

 

    

(Source: Natural Resources Defense Council)