heptachlor

Heptachlor is an organochlorine insecticide formerly widely used for agricultural pests and for termite control. It belongs to the cyclodiene family and is structurally related to other chlorinated pesticides such as chlordane. Heptachlor is highly lipophilic and persists in the environment, tending to accumulate in fatty tissues of organisms. It was manufactured as a mixture of technical isomers and was applied to crops, stored grain, soil, and wood treatments before usage restrictions reduced its use in many countries.

Once released, heptachlor persists in soils and sediments and can bioaccumulate through the food chain. The primary environmental breakdown product is heptachlor epoxide, which is also highly toxic and more persistent in some matrices. Because of its persistence and potential for long-range transport, many jurisdictions banned or severely restricted its use in the 1970s–1990s. It is listed under international agreements on persistent organic pollutants, and remediation of contaminated sites remains an ongoing concern.

Exposure to heptachlor and its metabolites can affect the nervous system, liver, and development in laboratory animals. In humans, epidemiological data are limited, but heptachlor is considered to have carcinogenic potential, and regulatory agencies advise minimizing exposure. Risk management focuses on restricting use, environmental cleanup, and monitoring of contaminated foods and soils.