DDTs

DDTs are a group of organochlorine pesticides whose best known member is DDT (dichlorodiphenyltrichloroethane). The term commonly includes its primary metabolites DDE (dichlorodiphenyldichloroethylene) and DDD (dichlorodiphenyldichloroethane).

They are highly lipophilic and persistent in the environment, with water solubility extremely low; they accumulate in fatty tissues of animals and magnify through the food chain, exposing wildlife and humans.

In insects they act as neurotoxins by interfering with voltage-gated sodium channels, causing prolonged nerve firing. Non-target effects include toxicity to birds, aquatic organisms, and some mammals.

Environmental concerns led to bans or restrictions in many countries. The Stockholm Convention on Persistent Organic Pollutants aims to eliminate or restrict DDT production and use, though limited, regulated use may be permitted for malaria vector control in certain regions under strict safeguards.

Synthesis and history: DDT was first synthesized in the 19th century and found to be highly effective as an insecticide in 1939 by Paul Müller, earning the Nobel Prize in 1948. Widespread use followed through the mid-20th century, but concerns about environmental and health impacts prompted phased withdrawal beginning in the 1960s to 1980s, with ongoing regulation in many jurisdictions.