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Posted by on Oct 3, 2017 in Tell Me Why |

Why Is DDT Dangerous?

Why Is DDT Dangerous?

After extensive use as a pesticide, DDT was found to have many harmful after-effects on human beings and animals. The control of insects was revolutionized by the introduction of DDT after the Second World War. It was employed to combat a wide range of insects which attacked food crops and was also instrumental in bringing the world malaria problem under control. But by the 1960s it was found that DDT affected the metabolism of many birds so much that their eggs became too fragile to survive.

As a result many species have nearly become extinct. Several kinds of fish have also been seriously affected. Large numbers of insects which served as food for both fish and birds have been destroyed. The effects of DDT on food for human consumption have been extremely serious. Food becomes poisonous if the amount of DDT in it exceeds a certain limit. However, such pesticides are now heavily restricted by most governments.

fragile bird eggs

Dichlorodiphenyltrichloroethane (DDT) is a colorless, tasteless, and almost odorless crystalline organochlorine known for its insecticidal properties and environmental impacts. First synthesized in 1874, DDT’s insecticidal action was discovered by the Swiss chemist Paul Hermann Müller in 1939. DDT was used in the second half of World War II to control malaria and typhus among civilians and troops. Müller was awarded the Nobel Prize in Physiology or Medicine “for his discovery of the high efficiency of DDT as a contact poison against several arthropods” in 1948.

By October 1945, DDT was available for public sale in the United States. Although it was promoted by government and industry for use as an agricultural and household pesticide, there were also concerns about its use from the beginning. Opposition to DDT was focused by the 1962 publication of Rachel Carson’s book Silent Spring. It cataloged environmental impacts that coincided with widespread use of DDT in agriculture in the United States, and it questioned the logic of broadcasting potentially dangerous chemicals into the environment with little prior investigation of their environment and health effects.

The book claimed that DDT and other pesticides had been shown to cause cancer and that their agricultural use was a threat to wildlife, particularly birds. Its publication was a seminal event for the environmental movement and resulted in a large public outcry that eventually led, in 1972, to a ban on DDT’s agricultural use in the United States. A worldwide ban on agricultural use was formalized under the Stockholm Convention on Persistent Organic Pollutants, but its limited and still-controversial use in disease vector control continues, because of its effectiveness in reducing malarial infections, balanced by environmental and other health concerns.

bald eagle

Along with the passage of the Endangered Species Act, the United States ban on DDT is a major factor in the comeback of the bald eagle (the national bird of the United States) and the peregrine falcon from near-extinction in the contiguous United States.

Content for this question contributed by Ian Winn, resident of Pacific Palisades, city of Los Angeles County, California, USA