Aryl halides exhibit lower reactivity in nucleophilic substitution due to the resonance effect, which imparts partial double bond character to the C—X bond, making bond cleavage more challenging compared to haloalkanes.

The use of DDT was banned in the United States in 1973. DDT’s chemical stability, fat solubility, and slow metabolism in animals led to its accumulation in fatty tissues, causing environmental concerns and contributing to its ban in the U.S., ...

DDT’s global use increased significantly after World War II due to its effectiveness against malaria-spreading mosquitoes and typhus-carrying lice. However, problems emerged in the late 1940s, including the development of insect resistance and high toxicity towards fish.

Paul Muller of Geigy Pharmaceuticals in Switzerland discovered the insecticidal effectiveness of DDT in 1939. He was awarded the Nobel Prize in Medicine and Physiology in 1948 for this discovery.