Endrin

Names
IUPAC name (1R,2S,3R,6S,7R,8S,9S,11R)-3,4,5,6,13,13-Hexachloro-10-oxapentacyclo[6.3.1.13,6.02,7.09,11]tridec-4-ene
Other names Mendrin, Compound 269, (1aR,2S,2aS,3S,6R,6aR,7R,7aS)-3,4,5,6,9,9-hexachloro-1a,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-dimethanonaphtho[2,3-b]oxirene, 1,2,3,4,10,10-Hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4-endo,endo-5,8-dimethanonaphthalene
Identifiers
CAS Number	72-20-8 Y
3D model (JSmol)	Interactive image
ChemSpider	21782117 Y
ECHA InfoCard	100.000.705
KEGG	C18124 Y
UNII	OB9NVE7YCL Y
CompTox Dashboard (EPA)	DTXSID6020561
InChI InChI=1S/C12H8Cl6O/c13-8-9(14)11(16)5-3-1-2(6-7(3)19-6)4(5)10(8,15)12(11,17)18/h2-7H,1H2/t2-,3+,4+,5-,6-,7+,10-,11+ Y Key: DFBKLUNHFCTMDC-RVVFZPGKSA-N Y InChI=1/C12H8Cl6O/c13-8-9(14)11(16)5-3-1-2(6-7(3)19-6)4(5)10(8,15)12(11,17)18/h2-7H,1H2/t2-,3+,4+,5-,6-,7+,10-,11+ Key: DFBKLUNHFCTMDC-RVVFZPGKBH
SMILES C1C2C3C(C1C4C2O4)C5(C(=C(C3(C5(Cl)Cl)Cl)Cl)Cl)Cl
Properties
Chemical formula	C12H8Cl6O
Molar mass	380.907 g/mol
Appearance	Colorless to tan crystalline solid
Density	1.77 g/cm3 [1]
Melting point	200 °C (392 °F; 473 K)
Solubility in water	0.23 mg/L[2]
Vapor pressure	2.6 x 10-5 Pa[1]
Hazards
NFPA 704 (fire diamond)	2 0 0
Flash point	noncombustible [3]
Lethal dose or concentration (LD, LC):
LD50 (median dose)	3 mg/kg (oral, monkey) 16 mg/kg (oral, guinea pig) 10 mg/kg (oral, hamster) 3 mg/kg (oral, rat) 7 mg/kg (oral, rabbit) 1.4 mg/kg (oral, mouse)[4]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.1 mg/m3 [skin][3]
REL (Recommended)	TWA 0.1 mg/m3 [skin][3]
IDLH (Immediate danger)	2 mg/m3[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Endrin is an organochloride with the chemical formula C₁₂H₈Cl₆O that was produced in 1950 and primarily used as an insecticide, as well as a rodenticide and piscicide. It is a colourless odorless solid, although commercial samples are often off-white. Endrin was also manufactured as an emulsifiable solution known commercially as Endrex.^[5] The compound became infamous as a persistent organic pollutant and for this reason it is banned in many countries.^[6]

In the environment endrin exists as either endrin aldehyde or endrin ketone and can be found mainly in bottom sediments of bodies of water.^{[7][better source needed]} Exposure to endrin can occur by inhalation, ingestion of substances containing the compound, or skin contact.^[8] Upon entering the body, it can be stored in body fats and can act as a neurotoxin on the central nervous system, which can cause convulsions, seizures, or even death.^[9]

Although^{[editorializing]} endrin is not currently classified as neither a mutagen,^[5] nor a human carcinogen, it is still a toxic chemical.^[10] The manufacturer cancelled all use of endrin in the United States by 1991. Food import concerns were raised due to the likelihood that some countries may have still been using endrin as a pesticide agent.^[8]

History

Endrin was first developed in 1950 by J. Hyman & Company and was used globally until the early 1970s. It was licensed to be manufactured by Shell International and Velsicol chemical companies. Production began in the United States by Shell and Velsicol and in the Netherlands by Shell. Due to its toxicity, it has been banned or severely restricted in many countries. In 1982, Shell discontinued the manufacturing of endrin.^[5]

It was estimated that 2.3-4.5 million kilograms of endrin were sold in the USA in 1962. In 1970, Japan imported 72,000 kilograms of endrin. From 1963, Bali used 171 to 10,700 kilograms of endrin annually for the production of rice paddies until use of the compound was discontinued in 1972.^[5] Taiwan reported to show higher levels of organochlorine pesticides including endrin, compared to other Asian countries such as Thailand and Vietnam. Over two million kilograms of organochlorine pesticides was estimated to be released into the environment annually in 1950s-1970s. Taiwan banned the use of endrin as psticides in 1971 and as toxic chemicals in 1989.^[11]

The Stockholm Convention on Persistent Organic Pollutants that came in effect May 2004 listed endrin as one of the 12 initial persistent organic pollutants (POPs) that have been causing adverse effects on humans as well as the ecosystem. The convention required the participating parties to take measures to eliminate or restrict the production of POPs.^[12]

Production

The synthesis of endrin begins with the condensation of hexachlorocyclopentadiene with vinyl chloride. The product is then dehydrochlorinated. Following reaction with cyclopentadiene, isodrin is formed. Epoxide formation by adding either peracetic acid or perbenzoic acid to the isodrin is the final step in synthesizing endrin.^[5]

Endrin is a stereoisomer of dieldrin.^[13]

Use

Endrin was formulated as emulsifiable concentrates (ECs), wettable powders (WPs), granules, field strength dusts (FSDs), and pastes. The product could then be applied by aircraft or by handheld sprayers in its various formulations.^[14]

Endrin has been used as an agriculture insecticide on tobacco, apple trees, cotton, sugar cane, rice, cereal, and grains.^[15] It is effective against a variety of species such as: cotton bollworms, corn borers, cut worms and grass hoppers.^[16] It has also been used to control rodents and birds.^[17]

As a pre-harvest treatment, endrin’s main use worldwide has been its application as a spray on cotton for the control of insects. In Australia, endrin is also used for insect control on tobacco. As a post-harvest treatment, endrin is sprayed onto the ground under the trees to control for rodents during autumn and spring. Its last use is as seed treatment for cotton seeds in the United States and bean seeds in Australia.^[18]

In Malaysia, a solution of endrin was used to rid mine pools and fish ponds of all fish prior to restocking, showing its effectiveness as a piscicide.^[19]

Environmental problems

Currently, the use of endrin is banned in countries that ratified the Stockholm Convention.^[6] Like related organochlorine pesticides, it is lipophilic and thusly it tends to accumulate in fatty tissues of organisms, mainly those dwelling in water. While some^[which?] estimates indicate its half-life in soil is over 10 years, the EPA has recently^[when?] released data indicating the half-life to be that of 14 years.^[20] In comparison with dieldrin, endrin is less persistent in the environment.^{[citation needed]}

Removal from the environment

Before endrin's toxicity was known, disposal methods consisted of land disposal. Due to endrin's toxicity, more precuatious measure have been taken. Two possible methods are chemical treatment (reductive dechlorination) or incineration. These disposal methods are applied to endrin and endrin aldehyde.^[8] Ketone endrins can be removed from the environment via photodecomposition, forming δ-ketoendrin, and microbial degradation. Microbial degradation depends on species in the soil as well as anaerobic conditions. Biodegradation is then aided by fungi and bacteria to form the major end product, delta-ketoendrin.^[14]

Health and safety

Endrin is toxic with an LD₅₀ of 3 mg/kg (oral, rat).^[21] Acute endrin poisoning in humans affects primarily the nervous system. Food contaminated with endrin caused several clusters of poisonings worldwide, especially affecting children.^{[citation needed]} Orally ingested endrin is eliminated mostly in feces.^[18] It is very toxic to aquatic organisms, namely fish, aquatic invertebrates, and phytoplankton. The U.S. EPA has set a freshwater acute criterion of 0.086 ug/L and a chronic criterion of 0.036 ug/L. In saltwater, the numbers are acute 0.037 and chronic 0.0023 ug/L.^[22] Human health contaminate criterion for water plus organism is 0.059 ug/L.^[23] The drinking water limit (maximum contaminant level) is set to 2 ppb.^[24]

For occupational exposures to endrin, OSHA and NIOSH have set exposure limits at 0.1 mg/m³.^[3]

Endrin was found to remain in the tissues of infected fish for up to one month. As such, use of endrin in fisheries has been advised against due to the zero tolerance of endrin levels in food products.^[19]