Final answer:
DDT is still used mainly to control disease vectors like malarial mosquitoes, particularly in areas where malaria poses a significant threat. Its use is limited due to its long-lasting environmental impact and sometimes as a last resort when other pesticides fail.
Step-by-step explanation:
Uses of DDT
DDT, a once widespread pesticide, is still used in certain contexts despite its environmental drawbacks. It has been found to be especially effective against malarial mosquitoes, which led to its extensive use after World War II to prevent the spread of malaria. For example, in the US South, DDT was used to help declare the US free of malaria by 1949. The persistence of DDT in the environment, as well as its resistance to breakdown, meant that even one or two applications per year on home interiors could drastically reduce mosquito populations.
However, concern about the hazards of DDT started growing, particularly after observations of its detrimental impact on the environment and wildlife. The bioaccumulation of DDT through the food chain led to thinner eggshells among birds of prey and was linked to a decline in their populations. As a result, the US government banned DDT for agricultural use in 1972. Despite this, DDT is still used in some parts of the world, primarily Mexico, and severely restricted to situations where alternative pesticides are ineffective or when it is the only available option to combat disease vectors such as malaria.
Controlling disease vectors such as those for malaria remains one of the main reasons DDT is still utilized. It has helped save millions of lives and reduce disease in areas where it is used. Recognizing both the human and ecological costs of DDT application, its current use is typically a result of weighing the benefits against the risks in areas where malaria poses a significant threat to human health.