Chlordecone

Chlordecone, better known under the brand name Kepone in the United States, is an organochlorine compound and a colourless solid. This compound is an obsolete insecticide related to Mirex and DDT. Its use was so disastrous that it is now prohibited in the western world, but only after many thousands of tonnes had been produced. Chlordecone is a known persistent organic pollutant (POP) that was banned globally by the Stockholm Convention on Persistent Organic Pollutants in 2009.
Toxicology.
The LC50 (LC = lethal concentration) is 35 μg/ L for "Etroplus maculatus", 22–95 μg/kg for blue gill and trout. Chlordecone bioaccumulates in animals by factors up to a million-fold.
Workers with repeated exposure suffer severe convulsions resulting from degradation of the synaptic junctions.
Chronic low level exposure appears to cause prostate cancer, and "significant excesses of deaths were observed for stomach cancer in women and pancreatic cancer in women".
Chlordecone has been found to act as an agonist of the GPER (GPR30), which interacts strongly with the estrogen sex hormone estradiol.
History.
In the US, chlordecone, commercialized under the brand name "Kepone", was produced by Allied Signal Company and LifeSciences Product Company in Hopewell, Virginia. The improper handling and dumping of the substance into the nearby James River (U.S.) in the 1960s and 1970s drew national attention to its toxic effects on humans and wildlife. The product is similar to DDT and is a degradation product of Mirex. Chlordecone was not federally regulated until after the Hopewell disaster, in which 29 factory workers were hospitalized with various ailments, including neurological. Chlordecone is cited amongst a handful of other noxious substances as the driver for Gerald Ford's half-hearted approval in 1976 of the Toxic Substances Control Act, which "remains one of the most controversial regulatory bills ever passed".
The history of chlordecone incidents are reviewed in "Who's Poisoning America?: Corporate Polluters and Their Victims in the Chemical Age" (1982).
In 2009, chlordecone was included in the Stockholm Convention on Persistent Organic Pollutants, which bans its production and use worldwide.
Case studies.
James River estuary.
In July 1975, Virginia Governor Mills Godwin Jr. shut down the James River to fishing for 100 miles, from Richmond to the Chesapeake Bay. This ban remained in effect for 13 years, until efforts to clean up the river began to show results.
Due to the pollution risks, many fishermen, marinas, seafood businesses, and restaurants, along with their employees along the river suffered economic losses. In 1981, a large group of these entities sued Allied Chemical in federal district court (Eastern District of Virginia), claiming special economic damages from Allied's negligent damage to the fish and wildlife. In a case that sometimes appears in law school courses on Remedies, the court rejected the traditional "economic-loss rule", which requires physical impact causing personal injury or property damage to receive economic damages, and instead allowed a limited group of the plaintiffs—the fishing boat owners, the marinas, and the bait and tackle shops—to recover economic damages from Allied Chemical.
French Antilles.
The French islands of Martinique and Guadeloupe are heavily contaminated with chlordecone, following years of its massive and unrestricted use on banana plantations. Despite a 1990 ban of the substance by France, the economically powerful banana planters lobbied intensively to obtain a derogation to use kepone until 1993, arguing that no alternative pesticide was available, which has since been disputed. Following the 1993 ban, the banana planters were discreetly granted derogations to use their remaining stocks, and a 2005 report prepared by the French National Assembly stated that it seemed likely that the chemical, under the name Curlone, continued to be illegally imported and used for years, including on sweet potato crops.
Since 2003, local authorities have restricted cultivation of crops because the soil has been seriously contaminated by chlordecone. A large-scale study by the public health agency "Santé publique France" published in 2018 showed that 95% of the inhabitants of Guadeloupe and 92% of those of Martinique are contaminated by the chemical. Guadeloupe has one of the highest prostate cancer diagnosis rates in the world.
Synthesis.
Chlordecone is made by dimerizing hexachlorocyclopentadiene and hydrolyzing to a ketone.