DDT (dichlorodiphenyltrichloroethane) was a popularly used insecticide in the 1940s, first in WWII and then in agriculture. In the 1950s, it was used to combat the spread of malaria by killing mosquitoes, but this project failed in tropical regions. Its widespread usage also caused high rates of DDT resistance in mosquitoes. American scientists were concerned with the possible dangers of DDT since it first began being used, but this issue did not gain attention until Rachel Carson published Silent Spring in 1962. This book claimed that pesticides, including DDT, were causing great harm to the environment and human health. Soon after, Silent Spring garnered great public attention, ad JFK ordered the investigation of Carson’s claims. The EDF (Environmental Defense Fund) was created with the aim to ban the use of DDT, which was discovered to be toxic to marine organisms and a chief cause of the thinning of birds’ eggshells. Its comprehensive uses were banned in 1972, but DDT is still used for disease vector control. For example, DDT is sprayed on the inside walls of houses to kill or repel mosquitoes, and this method supposedly greatly reduces environmental damage.
DDT is thought to be the major cause of the decline of birds of prey like bald eagles and peregrine falcons. Egg shell thinning makes the birds more susceptible to embryo deaths and egg breakage. DDT’s are also chemically similar to estrogens and can cause hormonal changes in animals. Thus, it is believed they also damage the reproductive system and decrease reproductive success. Some speculate that DDT is carcinogenic, but the CDC reports otherwise. Additionally, there is an ongoing debate between people who oppose the use of DDT for malaria control due to environmental concerns and those who support its use in order to save more livess. Regardless, the use of DDT is frowned upon in the US and most nations, yet it is still used in controlled manners.