Final answer:
DDT was a widely used pesticide in the mid-twentieth century due to its effectiveness against crop pests and malaria-carrying mosquitoes. However, its negative impacts on higher-level organisms and ecosystems led to its ban.
Step-by-step explanation:
DDT, which stands for dichloro, diphenyl, trichloroethane, was a pesticide widely used in the mid-twentieth century. It was particularly popular because it was inexpensive and persistent in the environment, making it effective against many crop pests and malaria-carrying mosquitoes. However, DDT had several negative impacts, including harming higher-level organisms through biomagnification and causing thinning of bird eggshells, which led to population declines in certain species. It was eventually banned due to these ecological and health concerns.