DDT pesticide,molecular model. DDT was widely used as a pesticide in the 1940s and 1950s,when it was used extensively in tropical countries,where insect-borne diseases such as malaria were a severe problem. Many insects developed resistance to it,however,and its widespread use had grave effects on other wildlife. It is highly persistent in the environment,and fish and bird numbers fell dramatically in many areas. It was banned in many countries,although it is still used in tropical countries as it is cheap and still reasonably effective. DDT is an abbreviation for its non- systematic name,dichlorodiphenyltrichloroethane. Atoms are shown as balls and are colour-coded: carbon (grey),chlorine (green) and hydrogen (white) |