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Defoliant

From Wikipedia, the free encyclopedia
This article is about chemicals used to remove leaves. For the animals that eat leaves, seeFolivore.For the removal of skin cells, seeExfoliation (cosmetology).For the chemical weapons programme, seeFoliant.
Defoliants are used as an aid in the harvesting of certain crops such as cotton.
2,4-D, one of the first chemical herbicides used as a defoliant.
U.S. ArmyHuey helicopterspraying Agent Orange over agricultural land during theVietnam War.

Adefoliantis anyherbicidalchemical sprayed or dusted on plants to cause theirleavesto fall off. Defoliants are widely used for the selective removal of weeds in managing croplands and lawns. Worldwide use of defoliants, along with the development of other herbicides andpesticides,allowed for theGreen Revolution,an increase in agricultural production in mid-20th century.[1]Defoliants have also been used in warfare as a means to deprive an enemy of food crops and/or hiding cover, most notably by theUnited Kingdomduring theMalayan Emergencyand theUnited Statesin theVietnam War.Defoliants were also used by Indonesian forces in various internal security operations.[2]

Use and application

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A primary application of defoliants is the selective killing of plants. Two of the oldest chemicalherbicidesused as defoliants are2,4-Dichlorophenoxyacetic acid(2,4-D) and2,4,5-Trichlorophenoxyacetic acid(2,4,5-T). 2,4-D and 2,4,5-T are absorbed by broad-leafed plants, killing them by causing excessive hormonal growth.[1]Thesephenoxy herbicideswere designed to selectively kill weeds and unwanted plants in croplands. They were first introduced at the beginning ofWorld War IIand became widespread in use in agriculture following the end of the War.

Defoliants have a practical use in the harvesting of certain crops, particularlycotton,in theUnited Statesas well as a number of other cotton-producing countries. The use of defoliants aids in the effective harvesting of cotton and finer lint quality.[3]The effectiveness of defoliant use in cotton harvesting depends on the type of defoliant(s) used, the number of applications, the amount applied, and environmental variables. Common harvest-aiding chemical defoliants include tribufos, dimethipin, andthidiazuron.According to a 1998 report by theU.S. Department of AgricultureNational Agricultural Statistics Service(NASS), tribufos and thidiazuron accounted for 60% of crop area that was treated by defoliants during that crop year.[4][5]

Examples of defoliants

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In Southeast Asia during the Vietnam War, theRainbow Herbicideswere a group of tactical-use chemicals used by theUnited Statesmilitary. The environmental destruction caused by this defoliation has been described by Swedish Prime MinisterOlof Palme,lawyers, historians and other academics as anecocide.[6][7][8][9][10]

Health and environmental effects

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In 1998, theU.S. Environmental Protection Agency(U.S. EPA) concluded that the use of agricultural defoliants led to increased risks of water contamination and dangers to freshwater andmarine life.[4]High doses of tribufos were labeled as a possiblecarcinogenand a toxin to freshwater and marineinvertebrates.Dimethipin has also been labeled as a possible human carcinogen.

A published study in theJournal of Agricultural and Food Chemistryreported that through successivesurface runoffevents in defoliated cotton fields, defoliant concentrations decreased exponentially within the test area and could negatively affect marine life in the runoff zones.[4]

Agent Orange,a defoliant used by theUnited Kingdomduring theMalayan Emergencyin the 1950s and theUnited Statesduring theVietnam Warto defoliate regions of Vietnam from 1961 to 1971,[11][12]has been linked to several long-term health issues. Agent Orange contains a mixture of 2,4-D and 2,4,5-T as well asdioxincontaminants. Members of the Air Force Ranch Hand and theArmy Chemical Corpswho served in theVietnam Warwere occupationally exposed toAgent Orangehave a higher incidence of diabetes, heart disease, hypertension, and chronic respiratory diseases.[13]

Among other occupations, farmers are at a significantly higher risk of developingAlzheimer's diseasedue to a greater chance of defoliant exposure.[14]

See also

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References

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  1. ^abZierler, David (2011).Invention of Ecocide.Athens, Georgia: University of Georgia Press.ISBN9786613110404.
  2. ^Aditjondro, George J. (2000).Ch 6. Ninjas, Nanggalas, Monuments, and Mossad Manuals.University of Pennsylvania Press.ISBN0-8122-1711-X.
  3. ^Snipes, Charles E.; Cathey, George W. (1992). "Evaluation of defoliant mixtures in cotton".Field Crops Research.28(4): 327–334.Bibcode:1992FCrRe..28..327S.doi:10.1016/0378-4290(92)90018-5.ISSN0378-4290.
  4. ^abcPotter, Thomas L.; Marti, Luz; Belflower, Sally; Truman, Clint C. (2000). "Multiresidue Analysis of Cotton Defoliant, Herbicide, and Insecticide Residues in Water by Solid-Phase Extraction and GC−NPD, GC−MS, and HPLC−Diode Array Detection".Journal of Agricultural and Food Chemistry.48(9): 4103–4108.doi:10.1021/jf9909104.ISSN0021-8561.PMID10995322.
  5. ^NASS (1999).Agricultural Chemical Usage 1998 Field Crops Summary.Washington, D.C.: U. S. Department of Agriculture National Agricultural Statistics and Economic Research Service. pg 141.
  6. ^Zierler, David (2011).The invention of ecocide: agent orange, Vietnam, and the scientists who changed the way we think about the environment.Athens, Ga.: Univ. of Georgia Press.ISBN978-0-8203-3827-9.
  7. ^"How Imperative Is It To Consider Ecocide As An International Crime?".IJLLR.2022-12-18.Retrieved2023-06-21.
  8. ^Falk, Richard A. (1973)."Environmental Warfare and Ecocide — Facts, Appraisal, and Proposals".Bulletin of Peace Proposals.4(1): 80–96.doi:10.1177/096701067300400105.ISSN0007-5035.JSTOR44480206.
  9. ^"Industrial disasters from Bhopal to present day: why the proposal to make 'ecocide' an international offence is persuasive – The Leaflet".theleaflet.in.2022-02-17.Retrieved2023-06-21.
  10. ^Giovanni, Chiarini (2022-04-01)."Ecocide: From the Vietnam War to International Criminal Jurisdiction? Procedural Issues In-Between Environmental Science, Climate Change, and Law".SSRN4072727.{{cite journal}}:Cite journal requires|journal=(help)
  11. ^Tow Fawthrop (June 14, 2004)."Vietnam's war against Agent Orange".bbc.co.uk.
  12. ^"Agent Orange Linked To Skin Cancer Risk".Science 2.0.27 August 2014.Retrieved17 September2014.
  13. ^Kang, Han K.; Dalager, Nancy A.; Needham, Larry L.; Patterson, Donald G.; Lees, Peter S.J.; Yates, Katherine; Matanoski, Genevieve M. (2006). "Health status of Army Chemical Corps Vietnam veterans who sprayed defoliant in Vietnam".American Journal of Industrial Medicine.49(11): 875–884.doi:10.1002/ajim.20385.ISSN0271-3586.PMID17006952.
  14. ^Tyas, Suzanne L; Manfreda, Jure; Strain, Laurel A; Montgomery, Patrick R (2001)."Risk factors for Alzheimer's disease: a population-based, longitudinal study in Manitoba, Canada".International Journal of Epidemiology.30(3): 590–597.doi:10.1093/ije/30.3.590.ISSN1464-3685.PMID11416089.
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