The use of DDT increased
enormously on a worldwide basis after World War II, primarily because
of its effectiveness against the mosquito that spreads malaria and lice
that carry typhus However, problems related to extensive use of DDT
began to appear in the late 1940s Many species of insects developed
resistance to DDT, and it was also discovered to have a high toxicity
towards fish The chemical stability of DDT and its fat solubility
compounded the problem