Mirex

Last updated
Mirex
Mirex.svg
Mirex 3D.png
Names
Preferred IUPAC name
Dodecachlorooctahydro-1H-1,3,4-(epimethanetriyl)cyclobuta[cd]pentalene
Other names
Perchlorodihomocubane
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.017.452 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 236-948-9
KEGG
MeSH D008917
PubChem CID
UNII
  • InChI=1S/C10Cl12/c11-1-2(12)7(17)4(14)3(13,5(1,15)9(7,19)20)6(1,16)10(21,22)8(2,4)18 X mark.svgN
    Key: GVYLCNUFSHDAAW-UHFFFAOYSA-N X mark.svgN
  • InChI=1/C10Cl12/c11-1-2(12)7(17)4(14)3(13,5(1,15)9(7,19)20)6(1,16)10(21,22)8(2,4)18
    Key: GVYLCNUFSHDAAW-UHFFFAOYAV
  • ClC12C(C3(Cl)Cl)(Cl)C4(Cl)C1(Cl)C(Cl)(Cl)C5(Cl)C4(Cl)C3(Cl)C52Cl
Properties
C10Cl12
Molar mass 545.55 g/mol
Melting point 485 °C (905 °F; 758 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Mirex is an organochloride that was commercialized as an insecticide and later banned because of its impact on the environment. This white crystalline odorless solid is a derivative of both cyclopentadiene and cubane. It was popularized to control fire ants but by virtue of chemical robustness and lipophilicity it was recognized as a bioaccumulative pollutant. The spread of the red imported fire ant was encouraged by the use of mirex, which also kills native ants that are highly competitive with the fire ants. The United States Environmental Protection Agency prohibited its use in 1976. [1] It is prohibited by the Stockholm Convention on Persistent Organic Pollutants.

Contents

Production and applications

Mirex was first synthesized in 1946, [2] but was not used in pesticide formulations until 1955. Mirex was produced by the dimerization of hexachlorocyclopentadiene in the presence of aluminium chloride.

Mirex is a stomach insecticide, meaning that it must be ingested by the organism in order to poison it. The insecticidal use was focused on Southeastern United States to control fire ants. Approximately 250,000 kg of mirex were applied to fields between 1962 and 1975 (US NRC, 1978). Most of the mirex was in the form of "4X mirex bait", which consists of 0.3% mirex in 14.7% soybean oil mixed with 85% corncob grits. Application of the 4X bait was designed to give a coverage of 4.2 g mirex/ha and was delivered by aircraft, helicopter or tractor. 1x and 2x bait were also used. Use of mirex as a pesticide was banned in 1978. The Stockholm Convention banned production and use of several persistent organic pollutants, and mirex is one of the "dirty dozen". [3]

Degradation

Much like other perchlorocarbons such as carbon tetrachloride, mirex does not burn easily; pyrolysis products are expected to include carbon dioxide, carbon monoxide, hydrogen chloride, chlorine, phosgene, and possibly other organochlorine species. Slow oxidation of mirex can be used to produce chlordecone ("Kepone"), a related insecticide that is also banned in most of the western world, but is more readily biodegraded. Sunlight degrades mirex to photomirex (8-monohydromirex) and 2,8-dihydromirex. [1] [4] [5]

Mirex is highly resistant to microbiological degradation. It only slowly dechlorinates to a monohydro derivative by anaerobic microbial action in sewage sludge and by enteric bacteria. Degradation by soil microorganisms has not been described.[ citation needed ]

Bioaccumulation and biomagnification

Mirex is highly cumulative and amount depends upon the concentration and duration of exposure. There is evidence of accumulation of mirex in aquatic and terrestrial food chains to harmful levels. After 6 applications of mirex bait at 1.4 kg/ha, high mirex levels were found in some species; turtle fat contained 24.8 mg mirex/kg, kingfishers, 1.9 mg/kg, coyote fat, 6 mg/kg, opossum fat, 9.5 mg/kg, and racoon fat, 73.9 mg/kg. In a model ecosystem with a terrestrial-aquatic interface, sorghum seedlings were treated with mirex at 1.1 kg/ha. Caterpillars fed on these seedlings and their faeces contaminated the water which contained algae, snails, Daphnia, mosquito larvae, and fish. After 33 days, the ecological magnification value was 219 for fish and 1165 for snails.[ citation needed ]

Although general environmental levels are low, it is widespread in the biotic and abiotic environment. Being lipophilic, mirex is strongly adsorbed on sediments.[ citation needed ]

Safety

Mirex is only moderately toxic in single-dose animal studies (oral LD50 values range from 3653000 mg/kg body weight). [6] It can enter the body via inhalation, ingestion, and via the skin. The most sensitive effects of repeated exposure in animals are principally associated with the liver, and these effects have been observed with doses as low as 1.0 mg/kg diet (0.05 mg/kg body weight per day), the lowest dose tested. At higher dose levels, it is fetotoxic (25 mg/kg in diet) and teratogenic (6.0 mg/kg per day). Mirex was not generally active in short-term tests for genetic activity. There is sufficient evidence of its carcinogenicity in mice and rats.[ citation needed ] Delayed onset of toxic effects and mortality is typical of mirex poisoning. Mirex is toxic for a range of aquatic organisms, with crustacea being particularly sensitive.[ citation needed ]

Mirex induces pervasive chronic physiological and biochemical disorders in various vertebrates. No acceptable daily intake (ADI) for mirex has been advised by FAO/WHO. IARC (1979) evaluated mirex's carcinogenic hazard and concluded that "there is sufficient evidence for its carcinogenicity to mice and rats. In the absence of adequate data in humans, based on above result it can be said, that it has carcinogenic risk to humans". Data on human health effects do not exist [ citation needed ].

Health effects

Per a 1995 ATSDR report mirex caused fatty changes in the livers, hyperexcitability and convulsion, and inhibition of reproduction in animals. It is a potent endocrine disruptor, interfering with estrogen-mediated functions such as ovulation, pregnancy, and endometrial growth. It also induced liver cancer by interaction with estrogen in female rodents. [7]

Related Research Articles

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<span class="mw-page-title-main">Chlordecone</span> Chemical compound

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<span class="mw-page-title-main">Lindane</span> Organochlorine chemical and an isomer of hexachlorocyclohexane

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<span class="mw-page-title-main">Parathion</span> Chemical compound

Parathion, also called parathion-ethyl or diethyl parathion, is an organophosphate insecticide and acaricide. It was originally developed by IG Farben in the 1940s. It is highly toxic to non-target organisms, including humans, so its use has been banned or restricted in most countries. In response to safety concerns, the less toxic but still dangerous analogue parathion methyl was later developed.

<span class="mw-page-title-main">Dicofol</span> Chemical compound

Dicofol is an insecticide, an organochlorine that is chemically related to DDT. Dicofol is a miticide that is very effective against spider mite. Its production and use is banned internationally under the Stockholm Convention.

<span class="mw-page-title-main">Chlorfenvinphos</span> Chemical compound

Chlorfenvinphos is an organophosphorus compound that was widely used as an insecticide and an acaricide. The molecule itself can be described as an enol ester derived from dichloroacetophenone and diethylphosphonic acid. Chlorfenvinphos has been included in many products since its first use in 1963. However, because of its toxic effect as a cholinesterase inhibitor it has been banned in several countries, including the United States and the European Union. Its use in the United States was discontinued in 1991.

<span class="mw-page-title-main">Pentachlorophenol</span> Chemical compound

Pentachlorophenol (PCP) is an organochlorine compound used as a pesticide and a disinfectant. First produced in the 1930s, it is marketed under many trade names. It can be found as pure PCP, or as the sodium salt of PCP, the latter of which dissolves easily in water. It can be biodegraded by some bacteria, including Sphingobium chlorophenolicum.

<span class="mw-page-title-main">Persistent organic pollutant</span> Organic compounds that are resistant to environmental degradation

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<span class="mw-page-title-main">Diazinon</span> Chemical compound

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<span class="mw-page-title-main">Dieldrin</span> Chemical compound

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<span class="mw-page-title-main">Fipronil</span> Chemical compound

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<span class="mw-page-title-main">Heptachlor</span> Chemical compound

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<span class="mw-page-title-main">Endrin</span> Chemical compound

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<span class="mw-page-title-main">Chlorethoxyfos</span> Chemical compound

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<span class="mw-page-title-main">Hexachlorocyclopentadiene</span> Chemical compound

Hexachlorocyclopentadiene (HCCPD), also known as C-56, Graphlox, and HRS 1655, is an organochlorine compound with the formula C5Cl6. It is a precursor to pesticides, flame retardants, and dyes. It is a colourless liquid, although commercial samples appear lemon-yellow liquid sometimes with a bluish vapour. Many of its derivatives proved to be highly controversial, as studies showed them to be persistent organic pollutants. An estimated 270,000 tons were produced until 1976, and smaller amounts continue to be produced today.

References

  1. 1 2 Robert L. Metcalf "Insect Control" in Ullmann’s Encyclopedia of Industrial Chemistry" Wiley-VCH, Wienheim, 2002. doi : 10.1002/14356007.a14_263
  2. H. J. Prins (1946). "Synthesis of Polychloro Compounds with Aluminium Chloride .XI.The Elimination of Hydrogen Chloride from Polychloro Compounds and the Formation of Cyclic Compounds -The Synthesis of Perchlorocyclopentadien". Recueil des Travaux Chimiques des Pays-Bas. 65 (7–8): 455–467. doi:10.1002/recl.19460650607.
  3. Kaiser KLE (1978). "Pesticide Report: The rise and fall of Mirex". Environmental Science and Technology. 12 (5): 520–528. Bibcode:1978EnST...12..520K. doi:10.1021/es60141a005.
  4. IPCS International Programme on Chemical Safety: Mirex – Health and Safety Guide No. 39 , 1990.
  5. Kelly L. Lambrych, John P. Hassett: Wavelength-dependent photoreactivity of mirex in Lake Ontario, Environmental Science and Technology, 2006, 40(3), 858–863; doi : 10.1021/es0511927.
  6. EL-Bayomey AA, IW Somak, and S. Branch. Embryotoxicity of the pesticide Mirex In vitro. Teratogenesis, Carcinogenesis, and Mutagenesis 2002, 22:239-249.
  7. Faroon O, Kueberuwa S, Smith L, DeRosa C (1995). "ATSDR evaluation of health effects of chemicals. II. Mirex and chlordecone: health effects, toxicokinetics, human exposure, and environmental fate". Toxicology and Industrial Health. 11 (6): 1–203. doi:10.1177/074823379501100601. PMID   8723616. S2CID   45676131.

Further reading