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IUPAC name
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
72-20-8 YesY
ChemSpider 21782117 YesY
Jmol-3D images Image
KEGG C18124 YesY
Molar mass 380.91 g·mol−1
Appearance Colorless to tan crystalline solid
Density 1.77 g/cm3 [1]
Melting point 200 °C (392 °F; 473 K) (decomposes)
0.23 mg/L[2]
Vapor pressure 2.6 x 10-5 Pa[1]
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point noncombustible [3]
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]
US health exposure limits (NIOSH):
TWA 0.1 mg/m3 [skin][3]
TWA 0.1 mg/m3 [skin][3]
2 mg/m3[3]
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY verify (what isYesY/N?)
Infobox references

Endrin is an organochloride with the chemical formula C12H8Cl6O that was first 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 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][8] Exposure to endrin can occur by inhalation, ingestion of substances containing the compound, or skin contact.[7] 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 endrin is not currently classified as neither a mutagen,[5] nor a human carcinogen, it is still a toxic chemical in other ways with detrimental effects.[10] Due to these toxic effects, 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.[7]


J. Hyman & Company first developed endrin in 1950. Shell International was licensed in the United States and in the Netherlands to produce it. Velsicol was the other producer in the Netherlands. Endrin was used globally until the early 1970s. Due to its toxicity, it was banned or severely restricted in many countries. In 1982, Shell discontinued its manufacturing.[5]

In 1962, an estimated 2.3-4.5 million kilograms of endrin were sold[by whom?] in the USA. In 1970, Japan imported 72,000 kilograms of endrin. From 1963 until 1972, Bali used 171 to 10,700 kilograms of endrin annually for the production of rice paddies until endrin use discontinued in 1972.[5] Taiwan reported to show higher levels[where?] of organochlorine pesticides including endrin, compared to other Asian countries such as Thailand and Vietnam. During the 1950s-1970s over two million kilograms of organochlorine pesticides were estimated of having been be released into the environment per year. Taiwan banned endrin's use as a pesticide in 1971 and regulated it as a toxic chemical in 1989.[11]

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


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]


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[by whom?] to control rodents and birds.[17]

As of 1970, endrin’s main use worldwide has been[clarification needed] its application as a spray on cotton to control insects. In Australia, endrin is[clarification needed] also used for insect control on tobacco. As a post-harvest treatment, endrin is[clarification needed] sprayed onto the ground under the trees to 'control' rodents during autumn and spring. It is[clarification needed] used as seed treatment for cotton seeds in the United States and bean seeds in Australia.[18]

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

Environmental behavior[edit]

Insecticides like dieldrin and endrin have been shown to persist for decades in the environment.[20] A definitive detection of the residues was not possible until 1971 when mass spectrometer started being used as a detector in gas chromatography.[21] Detection of these chemicals in the environment has been reported across the world up to 2005,[20] even though the frequency is low[clarification needed] due to its relatively small-scale use and very low concentrations.[21]

Endrin regularly enters the environment when applied to crops or when rain washes it off. It has been found in water, sediments, atmospheric air and biotic environment, even after uses have been stopped.[22] Organochlorine pesticides strongly resist degradation, are poorly soluble in water but highly soluble in lipids, which is called lipophilic.[21] This leads to bioaccumulation in fatty tissues of organisms, mainly those dwelling in water. A high bioconcentration factor of 1335-10,000 has been reported in fish.[23] Endrin binds very strongly to organic matter in soil and aquatic sediments due to their high adsorption coefficient, [21] making it less likely to leach into groundwater, even though contaminated groundwater samples have been found. In 2009, EPA released data indicating that the endrin in soil could last up to 14 years or more.[23] The extent of endrin's persistence depends highly on local conditions. For example, high temperature (230°C) or intense sunlight leads to more rapid breakdown of endrin into endrin ketone and endrin aldehyde, however, this breakdown is less than 5%.[24][page needed]

Removal from the environment[edit]

Before endrin's toxicity was known[clarification needed], disposal methods consisted of land disposal. Due to endrin's toxicity, more precuatious measure have been taken[by whom?]. Two possible methods are chemical treatment (reductive dechlorination) or incineration. These disposal methods are applied[by whom?] to endrin and endrin aldehyde.[7] 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. fungi and bacteria aid biodegradation to form the major end product, delta-ketoendrin.[14] Even though endrin binds very strongly to soil, phytoremediation has been proposed[by whom?] using crops in the Cucurbitaceae family. As of 2009, exact mechanisms behind the plant uptake of endrin have not been understood, requiring much[quantify] more research in uptake mechanisms for practical application.[20]

Health and safety[edit]

Exposure to endrin can occur by inhalation, ingestion of substances containing the compound, or by skin contact.[7]

Upon entering the body, it distributes in body fats, where it can be stored. Acute endrin poisoning in humans affects primarily the central nervous system. There, it can act as a neurotoxin, which in the acute case means seizures, or even death.[25] Endrin is acutely toxic with an LD50 of 3 mg/kg (oral, rat).[26] 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.[27] Endrin was found to remain in the tissues of infected fish for up to one month.[19]


In the United States, endrin has been regulated by the EPA. It 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.[27] The human health contaminate criterion for water plus organism is 0.059 ug/L.[28] The drinking water limit (maximum contaminant level) is set to 2 ppb.[29] Use of endrin in fisheries has been advised against due to the zero tolerance of endrin levels in food products.[19] For occupational exposures to endrin, OSHA and NIOSH have set exposure limits at 0.1 mg/m3.[3] As of 2004, the use of endrin is banned in countries that ratified the Stockholm Convention.[6]

See also[edit]


  1. ^ a b "Endrin". Deutsche Gesellschaft für Technische Zusammenarbeit. Retrieved 13 March 2015. 
  2. ^ "Endrin (PDS)". IPCS. Retrieved 13 March 2015. 
  3. ^ a b c d e "NIOSH Pocket Guide to Chemical Hazards #0252". National Institute for Occupational Safety and Health (NIOSH). 
  4. ^ "Endrin". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). 4 December 2014. Retrieved 19 March 2015. 
  5. ^ a b c d e van Esch, G. T.; van Heemstra-Lequin, E. A. H. (1992). "Environmental Health Criteria 130: Endrin". International Programme on Chemical Safety. World Health Organization. Retrieved March 2015. 
  6. ^ a b "Stockholm Convention on Persistent Organic Pollutants (POPs)". Commonwealth of Australia: Department of the Environment. 2013. Retrieved March 2015. 
  7. ^ a b c d e "Toxicological Profile for Endrin". Agency for Toxic Substances and Disease Registry. United States Department of Health and Human Services. August 1996. Retrieved March 2015. 
  8. ^ Berry, Walter (August 2003). "Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Endrin". EPA: Office of Research and Development. 
  9. ^ "Some Acute and Chronic Effects of Endrin on the Brain". Federal Aviation Administration: Office of Aviation Medicine. July 1970. Retrieved 14 March 2015. 
  10. ^ "Endrin (CASRN 72-20-8)". Integrated Risk Information System. United States Environmental Protection Agency. September 1988. Retrieved March 2015. 
  11. ^ Tsai, Wen-Tien (12 October 2010). "Current Status and Regulatory Aspects of Pesticides Considered to be Persistent Organic Pollutants (POPs) in Taiwan". International Journal of Environmental Research and Public Health 7 (10): 3615–3627. doi:10.3390/ijerph7103615. Retrieved 3 March 2015. 
  12. ^ "History of the negotiations of the Stockholm Convention". Stockholm Convention. Stockholm Convention. Retrieved 20 March 2015. 
  13. ^ "Organochlorine Pesticides Overview: Endrin". CDC - National Biomonitoring Program. Center for Disease Control and Prevention. December 2013. Retrieved March 2015. 
  14. ^ a b "Endrin: Health and Safety Guide No. 60". International Programme on Chemical Health. World Health Organization. 1991. Retrieved March 2015. 
  15. ^ "Basic Information about Endrin in Drinking Water". United States Environmental Protection Agency. February 9, 2014. Retrieved March 2015. 
  16. ^ "Data Sheets on Pesticides No. 1: Endrin". International Programme on Chemical Safety. World Health Organization; Food and Agriculture Organization. January 1975. Retrieved March 2015. 
  17. ^ "Healthy Milk, Healthy Baby - Chemical Pollution and a Mother's Milk". National Resources Defense Council. 25 March 2005. Retrieved March 2015. 
  18. ^ a b "1970 Evaluations of Some Pesticide Residues in Food: The Monographs - Endrin". International Programme on Chemical Safety. World Health Organization; Food and Agriculture Organization of the United Nations. 1971. Retrieved March 2015. 
  19. ^ a b c "Integrated Management Techniques to Control Nonnative Fishes". Upper Midwest Environmental Sciences Center. United States Geological Survey. December 2003. Retrieved March 2015. 
  20. ^ a b c Matsumoto, Emiko; Kawanaka, Youhei; Yun, Sun-Ja; Oyaizu, Hiroshi (4 July 2009). "Bioremediation of the organochlorine pesticides, dieldrin and endrin, and their occurrence in the environment". Applied Microbiology and Biotechnology 84 (2): 205–216. doi:10.1007/s00253-009-2094-5. 
  21. ^ a b c d Zitko, Vladimir (2003). Persistent Organic Pollutants. Berlin Heidelberg: Springer-Verlag. pp. 47–90. ISBN 978-3-540-43728-4. Retrieved 25 March 2015. 
  22. ^ Chopra, A. K.; Sharma, Mukesh Kumar; Chamoli, Shikha (February 2011). "Bioaccumulation of organochlorine pesticides in aquatic system—an overview". Environmental Monitoring and Assessment 173 (1-4): 905–916. doi:10.1007/s10661-010-1433-4. 
  23. ^ a b "Technical Factsheet on: Endrin". www.epa.gov. United States Environmental Protection Agency. Retrieved 26 March 2015. 
  24. ^ "TOXICOLOGICAL PROFILE FOR ENDRIN". www.atsdr.cdc.gov. U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES. Retrieved 26 March 2015. 
  25. ^ "Some Acute and Chronic Effects of Endrin on the Brain". Federal Aviation Administration: Office of Aviation Medicine. July 1970. Retrieved 14 March 2015. 
  26. ^ Endrin in the ChemIDplus database
  27. ^ a b "Ambient Water Quality Criteria for Endrin". EPA Water. United States Environmental Protection Agency. October 1980. Retrieved March 2015. 
  28. ^ "Human Health Criteria". EPA Water. United States Environmental Protection Agency. December 2003. Retrieved March 2015. 
  29. ^ "Drinking Water Contaminants: National Primary Drinking Water Regulations". EPA Water. United States Environmental Protection Agency. May 2009. Retrieved March 2015.