This article needs more reliable medical references for verification or relies too heavily on primary sources .(January 2015) |
Names | |
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Preferred IUPAC name (2,4,5-Trichlorophenoxy)acetic acid | |
Other names 2,4,5-Trichlorophenoxyacetic acid 2,4,5-T Trioxone | |
Identifiers | |
3D model (JSmol) | |
2055620 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.002.068 |
EC Number |
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434052 | |
KEGG | |
PubChem CID | |
RTECS number |
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UNII | |
UN number | 2811 3345 3348 2765 |
CompTox Dashboard (EPA) | |
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Properties | |
C8H5Cl3O3 | |
Molar mass | 255.48 g/mol |
Appearance | Off-white to yellow crystalline solid |
Odor | odorless |
Density | 1.80 g/cm3, 20 °C |
Melting point | 154 to 158 °C (309 to 316 °F; 427 to 431 K) |
Boiling point | decomposes [1] |
238 mg/kg (30 °C) | |
Vapor pressure | 1×10−7 mmHg [1] |
Hazards | |
GHS labelling: | |
Warning | |
H302, H315, H319, H335, H410 | |
P261, P264, P270, P271, P273, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P391, P403+P233, P405, P501 | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 381 mg/kg (guinea pig, oral) 300 mg/kg (rat, oral) 425 mg/kg (hamster, oral) 242 mg/kg (mouse, oral) [2] |
NIOSH (US health exposure limits): | |
PEL (Permissible) | TWA 10 mg/m3 [1] |
REL (Recommended) | TWA 10 mg/m3 [1] |
IDLH (Immediate danger) | 250 mg/m3 [1] |
Related compounds | |
Related compounds | 2,4-D auxin |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
2,4,5-Trichlorophenoxyacetic acid (also known as 2,4,5-T), a synthetic auxin, is a chlorophenoxy acetic acid herbicide used to defoliate broad-leafed plants. It was developed in the late 1940s, synthesized by reaction of 2,4,5-Trichlorophenol and chloroacetic acid. It was widely used in the agricultural industry until being phased out, starting in the late 1970s due to toxicity concerns. Agent Orange, a defoliant used by the British in the Malayan Emergency and the U.S. in the Vietnam War, was equal parts 2,4,5-T and 2,4-D (2,4-dichlorophenoxyacetic acid). 2,4,5-T itself is toxic with a NOAEL of 3 mg/kg/day and a LOAEL of 10 mg/kg/day. [3] Agent Pink contained 100% 2,4,5-T (dioxin contaminates included). Additionally, the manufacturing process for 2,4,5-T contaminates this chemical with trace amounts of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). [4] TCDD is a carcinogenic persistent organic pollutant with long-term effects on the environment. With proper temperature control during production of 2,4,5-T, TCDD levels can be held to about .005 ppm.[ citation needed ] Before the TCDD risk was well understood, early production facilities lacked proper temperature controls and individual batches tested later were found to have as much as 60 ppm of TCDD.[ citation needed ]
In 1970, the United States Department of Agriculture halted the use of 2,4,5-T on all food crops except rice, and in 1985, the EPA terminated all remaining uses in the U.S. of this herbicide. In Canada, the use and sale of 2,4,5-T was prohibited after 1985. [5] The international trade of 2,4,5-T is restricted by the Rotterdam Convention. 2,4,5-T has since largely been replaced by dicamba and triclopyr.
Human health effects from 2,4,5-T at low environmental doses or at biomonitored levels from low environmental exposures are unknown. Intentional overdoses and unintentional high dose occupational exposures to chlorophenoxy acid herbicides have resulted in weakness, headache, dizziness, nausea, abdominal pain, myotonia, hypotension, renal and hepatic injury, and delayed neuropathy. Cometabolism of 2,4,5-T is possible to produce 3,5-dichlorocatechol [6] which, in turn, can be degraded by Pseudomonas bacteria. [7] IARC considers the chlorophenoxyacetic acids group of chemicals as possibly carcinogenic to humans. [8]
In 1963 a production vessel for 2,4,5-T exploded in the Philips-Duphar plant in the Netherlands. [9] Six workers that cleaned up afterwards got seriously intoxicated and developed chloracne. [9] After twelve years, four of the six cleaners had died.[ citation needed ]
Agent Orange is a chemical herbicide and defoliant, one of the tactical use Rainbow Herbicides. It was used by the U.S. military as part of its herbicidal warfare program, Operation Ranch Hand, during the Vietnam War from 1961 to 1971. The U.S. was strongly influenced by the British who used Agent Orange during the Malayan Emergency. It is a mixture of equal parts of two herbicides, 2,4,5-T and 2,4-D. In addition to its damaging environmental effects, traces of dioxin found in the mixture have caused major health problems and deformities for many individuals who were exposed, and their children.
Polychlorinated dibenzodioxins (PCDDs), or simply dioxins, are a group of long-lived polyhalogenated organic compounds that are primarily anthropogenic, and contribute toxic, persistent organic pollution in the environment.
Operation Ranch Hand was a U.S. military operation during the Vietnam War, lasting from 1962 until 1971. Largely inspired by the British use of chemicals 2,4,5-T and 2,4-D during the Malayan Emergency in the 1950s, it was part of the overall herbicidal warfare program during the war called "Operation Trail Dust". Ranch Hand involved spraying an estimated 19 million U.S. gallons (72,000 m3) of defoliants and herbicides over rural areas of South Vietnam in an attempt to deprive the Viet Cong of food and vegetation cover. Areas of Laos and Cambodia were also sprayed to a lesser extent. According to the Vietnamese government, the chemicals caused 400,000 deaths. The United States government has described these figures as "unreliable".
The Seveso disaster was an industrial accident that occurred around 12:37 pm on 10 July 1976, in a small chemical manufacturing plant approximately 20 kilometres (12 mi) north of Milan in the Lombardy region of Italy. It resulted in the highest known exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in residential populations, which gave rise to numerous scientific studies and standardized industrial safety regulations, including the European Union's Seveso III Directive. This accident was ranked eighth in a list of the worst man-made environmental disasters by Time magazine in 2010.
Chloracne is an acneiform eruption of blackheads, cysts, and pustules associated with exposure to certain halogenated aromatic compounds, such as chlorinated dioxins and dibenzofurans. The lesions are most frequently found on the cheeks, behind the ears, in the armpits and groin region.
Chemical hazards are hazards present in hazardous chemicals and hazardous materials. Exposure to certain chemicals can cause acute or long-term adverse health effects. Chemical hazards are usually classified separately from biological hazards (biohazards). Chemical hazards are classified into groups that include asphyxiants, corrosives, irritants, sensitizers, carcinogens, mutagens, teratogens, reactants, and flammables. In the workplace, exposure to chemical hazards is a type of occupational hazard. The use of personal protective equipment may substantially reduce the risk of adverse health effects from contact with hazardous materials.
A defoliant is any herbicidal chemical sprayed or dusted on plants to cause their leaves to 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 and pesticides, allowed for the Green Revolution, an increase in agricultural production in mid-20th century. Defoliants have also been used in warfare as a means to deprive an enemy of food crops and/or hiding cover, most notably by the United Kingdom during the Malayan Emergency and the United States in the Vietnam War. Defoliants were also used by Indonesian forces in various internal security operations.
Toluene diisocyanate (TDI) is an organic compound with the formula CH3C6H3(NCO)2. Two of the six possible isomers are commercially important: 2,4-TDI (CAS: 584-84-9) and 2,6-TDI (CAS: 91-08-7). 2,4-TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively. It is produced on a large scale, accounting for 34.1% of the global isocyanate market in 2000, second only to MDI. Approximately 1.4 billion kilograms were produced in 2000. All isomers of TDI are colorless, although commercial samples can appear yellow.
Agent Purple is the code name for a powerful herbicide and defoliant used by the U.S. military in their herbicidal warfare program during the Vietnam War. The name comes from the purple stripe painted on the barrels to identify the contents. Largely inspired by the British use of herbicides and defoliants during the Malayan Emergency, it was one of the so-called "Rainbow Herbicides" that included the more infamous Agent Orange. Agent Purple and Orange were also used to clear brush in Canada.
Herbicidal warfare is the use of substances primarily designed to destroy the plant-based ecosystem of an area. Although herbicidal warfare use chemical substances, its main purpose is to disrupt agricultural food production and/or to destroy plants which provide cover or concealment to the enemy, not to asphyxiate or poison humans and/or destroy human-made structures. Herbicidal warfare has been forbidden by the Environmental Modification Convention since 1978, which bans "any technique for changing the composition or structure of the Earth's biota".
Agent Green is the code name for a powerful herbicide and defoliant used by the U.S. military in its herbicidal warfare program during the Vietnam War. The name comes from the green stripe painted on the barrels to identify the contents. Largely inspired by the British use of herbicides and defoliants during the Malayan Emergency, it was one of the so-called "Rainbow Herbicides". Agent Green was only used between 1962 and 1964, during the early "testing" stages of the spraying program.
Picloram is a systemic herbicide used for general woody plant control. It also controls a wide range of broad-leaved weeds, but most grasses are resistant. A chlorinated derivative of picolinic acid, picloram is in the pyridine family of herbicides.
Agent Pink is the code name for a powerful herbicide and defoliant used by the U.S. military in its herbicidal warfare program during the Vietnam War. The name comes from the pink stripe painted on the barrels to identify the contents. Largely inspired by the British use of herbicides and defoliants during the Malayan Emergency, it was one of the rainbow herbicides that included the more infamous Agent Orange. Agent Pink was only used during the early "testing" stages of the spraying program before 1964.
The Rainbow Herbicides are a group of tactical-use chemical weapons used by the United States military in Southeast Asia during the Vietnam War. Success with Project AGILE field tests in 1961 with herbicides in South Vietnam was inspired by the British use of herbicides and defoliants during the Malayan Emergency in the 1950s, which led to the formal herbicidal program Trail Dust. Herbicidal warfare is the use of substances primarily designed to destroy the plant-based ecosystem of an agricultural food production area and/or to destroy dense foliage which provides the enemy with natural tactical cover.
Dioxins and dioxin-like compounds (DLCs) are a group of chemical compounds that are persistent organic pollutants (POPs) in the environment. They are mostly by-products of burning or various industrial processes or, in the case of dioxin-like PCBs and PBBs, unwanted minor components of intentionally produced mixtures.
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin (sometimes shortened, though inaccurately, to simply 'dioxin') with the chemical formula C12H4Cl4O2. Pure TCDD is a colorless solid with no distinguishable odor at room temperature. It is usually formed as an unwanted product in burning processes of organic materials or as a side product in organic synthesis.
2,4-Dichlorophenoxyacetic acid is an organic compound with the chemical formula Cl2C6H3OCH2CO2H. It is usually referred to by its ISO common name 2,4-D. It is a systemic herbicide that kills most broadleaf weeds by causing uncontrolled growth, but most grasses such as cereals, lawn turf, and grassland are relatively unaffected.
The Enlist Weed Control System is an agricultural system that includes seeds for genetically modified crops that are resistant to Enlist and the Enlist herbicide; spraying the herbicide will kill weeds but not the resulting crop. The system was developed by Dow AgroSciences, part of Dow Chemical Company. In October 2014 the system was registered for restricted use in Illinois, Indiana, Iowa, Ohio, South Dakota and Wisconsin by the US Environmental Protection Agency. In 2013, the system was approved by Canada for the same uses.
Agent Orange is a herbicide, classified as a defoliant, that was used most notably by the U.S. military during the Vietnam War. Its primary purpose was strategic deforestation, destroying the forest cover and food resources necessary for the implementation and sustainability of the North Vietnamese style of guerilla warfare. The U.S. Agent Orange usage reached an apex during Operation Ranch Hand, in which the material was sprayed over 4.5 million acres of land in Vietnam from 1961 to 1971.
2,4,5-Trichlorophenol (TCP) is an organochloride with the molecular formula C6H3Cl3O. It has been used as a fungicide and herbicide. Precursor chemical used in the production of 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) and hexachlorophene involves the intermediate production of 2,4,5-trichlorophenol (TCP) and the formation of 2,3,7,8-Tetrachlorodibenzodioxin (TCDD, commonly referred to simply as dioxin) as an unwanted by-product. In the course of purifying the hexachlorophene, still bottom wastes were created with concentrated levels of TCP and dioxin.