What was DDT initially used for, and how does it work as a pesticide?

Discuss the pesticide dichlorodiphenyltrichloroethane (DDT). What was DDT initially used for, and how does it work as a pesticide? Explain the benefits of DDT, and then discuss how DDT moves through the environment.

 A population of individuals was exposed to lead contamination in drinking water at the concentration of 27 parts per billion (ppb).