Pressure from environmental groups in developed countries reduced the use of DDT, which is now effectively banned - only a few countries continue to use it. However, the rate at which its use has declined has been precisely in step with a resurgence in the incidence of malaria, which now kills a million people a year, most of them children and pregnant women.
This raises a classic question of balance of risk and benefit. DDT is cheap and effective. But it has a lethal effect on one part of the eco-system.