Biological Magnification
Wildlife can be harmed and even driven to extinction by the process called biological magnification This term refers to an increase in concentration of a no degradable (or slowly degradable) substance in organisms as it is passed upward through food chains. An example is the peregrine falcon, which nearly went extinct as a result of biological magnification of DDT. This synthetic pesticide was first used in the tropics during World War II to kill mosquitos that carried malaria. Later in Europe it helped control body lice that were transmitting a bacterium that causes typhus. After the war, it seemed like a good idea to use DDT against agricultural, garden, or forest pests DDT can build up in the tissues of animals that come into contact with it in the air, water, or food, After the war, it began to move through the global environment, infiltrate food webs, and affect organisms in ways that no one had predicted. In cities where DDT was sprayed to control Dutch elm disease, songbirds started dying In streams flowing through forests where DDT was sprayed to control spruce budworms, salmon started dying In croplands sprayed to control one kind of pest, new kinds of pests moved in. DDT was killing off natural predators that had been keeping pest populations in check