DDT

DDT (dichlorodiphenyltrichloroethane) is a chemical used in agriculture and public health to kill insects. It is an organochlorine compound, meaning its structure contains carbon and chlorine. It is a white solid that does not dissolve in water but dissolves in oils and fats.

DDT came into use from the 1940s onward, particularly against malaria-carrying mosquitoes and agricultural pests. Its agricultural use was restricted or banned in many countries from the 1970s onward, after it was discovered to persist in the environment and accumulate through the food chain.

Chemical properties

DDT breaks down slowly in the environment. Because it dissolves in fats, it accumulates in fatty tissues of animals. This process, known as bioaccumulation, causes concentrations to increase in animals at higher levels of the food chain, such as predatory birds. A breakdown product, DDE, also persists.

Use in public health

Malaria control programs have used a method called indoor residual spraying—applying DDT to the interior walls and eaves of houses to kill mosquitoes when they rest. Global health authorities continue to permit limited public health use in some malaria-endemic countries, subject to conditions and reporting requirements.

Legal regulation

DDT was added to the Stockholm Convention on persistent organic pollutants (POPs). The convention banned agricultural use but created an exemption for controlled use against malaria-carrying insects, with participating countries required to submit reports.

Debate

An ongoing debate exists between the benefits of malaria prevention and possible health and environmental risks. Some researchers point to potential effects on bird reproduction and DDT levels in humans, while others emphasize that alternatives may be costly for many countries.