DDT

Definition

A persistent organochlorine insecticide (dichlorodiphenyltrichloroethane) that acts as a contact and stomach poison against arthropods. DDT targets the voltage-gated sodium channels of neurons, causing repetitive firing and paralysis. It was widely deployed in the 1940s–1960s for agricultural pest control and public health campaigns against malaria, typhus, and other vector-borne diseases, but its environmental persistence, bioaccumulation in food webs, and toxicity to non-target organisms—particularly birds and aquatic life—led to restrictions and bans in most developed nations by the 1970s. Resistance development in target populations, especially anopheline mosquitoes, has limited its efficacy in many regions.

Etymology

Acronym for dichlorodiphenyltrichloroethane, the full chemical name describing its structure: two chlorinated phenyl rings attached to a trichloroethane backbone.

Example

Indoor residual spraying of DDT on hut walls in the 1950s WHO anti-malaria campaign reduced Anopheles gambiae populations and malaria incidence in parts of Africa and Asia, though resistance alleles at the kdr (knockdown resistance) locus in mosquito sodium channel genes eventually spread through many treated populations.

Synonyms

• dichlorodiphenyltrichloroethane

Related Terms

• organochlorine
• insecticide resistance
• vector control
• bioaccumulation
• persistent organic pollutant
• Malaria
• Anopheles
• knockdown resistance
• integrated vector management

Usage Notes

DDT remains technically available for public health use under the Stockholm Convention in regions with ongoing malaria transmission where no effective alternatives exist. Specialists distinguish between DDT's historical agricultural applications (now widely prohibited) and its current restricted deployment for indoor residual spraying against malaria vectors. The compound exists as several isomers, with p,p'-DDT being the most insecticidally active. DDT and its metabolite DDE are lipid-soluble and biomagnify through trophic levels, with documented eggshell thinning in raptorial birds being a classic example of sublethal ecological impact.