2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) is a chlorophenoxy acid herbicide that is no longer registered for use in the United States. Ester forms of 2,4,5-T and 2,4-D were used as defoliants in the Vietnam War (e.g., Agent Orange) and concern about contamination with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) led to the discontinuation of 2,4,5-T use as an herbicide in 1985.

Chemical Description

2,4,5-T is produced commercially by condensation of sodium chloroacetate with sodium 2,4,5-trichlorophenoxide. At high temperatures the action of alkali on 2,4,5-trichlorophenol can produce some 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, or dioxin). It is impossible for manufacturers to produce 2,4,5-T without some TCDD contamination.

Technical grade 2,4,5-T (94%) takes the form of colorless crystals. Melting point is 153-156 oC. The vapor pressure is 700 nPa at 25oC. It is sparingly soluble in water (150 mg/l), but its salts with alkali metals and amines are water soluble. Esters of 2,4,5-T are insoluble in water but soluble in oils (#Rotterdam convention, Annex III).


It was used for selective control of weeds in cereal crops and lawns, nettles in pasture and woody weeds in forestry, particularly with conifers (#INCHEM).

Trade names: Dacamine, Ded-Weed, Farmco Fence Rider, Forron, Inverton 245, Line Rider, T-Nox, Transamine, Brushwood Killer, Brush-Rhap, Brushtox, Esterone, Fruitone A, Reddon, Spontox, Tormona, Tributon, Veon 245, Verton 2T, Visko Rhap Low Volatile Ester, Amine 2,4,5-T for Rice, Super D Weedone, Trinoxol, Weedar, Weedone (#Rotterdam convention, Annex III).

Routes of Exposure and Metabolism

The substance can be absorbed into the body by inhalation of its aerosol and by ingestion (#ICSC). Once absorbed into the body, 2,4,5-T is eliminated mostly unchanged in the urine, with an elimination half-life of approximately 19 hours (#CDC).

2,4,5-T on the soil may be degraded chemically or biologically, volatilized, absorbed in the soil, or leached beyond the depth of plant roots. 2,4,5-T is moderately mobile in sandy and clay soils. Half-life on grass is 8-17 days, in soils 21-24 days. Normally, only small amounts enter water, where it does not persist as it is absorbed by clay or biota within a few days. Esters of 2,4,5-T are usually hydrolyzed within a few days. There is no significant bioaccumulation (#Rotterdam convention, Annex III).

Human Health Effects

Acute Health Effects
Inhalation of 2,4,5-T can cause cough and sore throat, and exposure to eyes leads to redness and pain. Ingestion results in diarrhea, drowsiness, headache, nausea, and vomiting (#ICSC).
Chronic Health Effects
2,4,5-T is listed as a possible carcinogen on the IARC Carcinogens list. State of California Proposition Carcinogen List ranks 2,4,5-T as a "known" carcinogen (#PANNA).

The EU lists it as endocrine disrupting chemical. Also, it is listed as a probable endocrine disruptor by the Illinois EPA (#PANNA).

Environmental Health Effect

In general, the long-term ecological impact of 2,4,5-T can be considered low, but increases with the level of TCDD impurity.

2,4,5-T is phytotoxic to almost all broad-leaved crops, especially cotton, tomatoes, ornamentals, grapes, and fruit trees.

Toxicity to organisms

Fish: Eight-day dietary LC50 for bobwhite quail, 2776 mg/kg diet; LC50 for rainbow trout, 350, and for carp, 355 mg/l (96 hours). TCDD level not specified.
Birds: Low toxicity to birds.
Bees: Honey bee LD50 1.01 µg/bee in laboratory (48 hr, 65% relative humidity, 26.7oC) (#Rotterdam convention, Annex III).


Given the unavailability of 2,4,5-T, the general population is unlikely to be exposed to 2,4,5-T (#CDC).


Its international trade is restricted by the Rotterdam Convention. In the USA 2,4,5-T is regulated under Air Contaminants (Occupational and Safety Health Act), Hazardous Constituents (Resource Conservation and Recovery Act), Hazardous Substances (Superfund), Registered Pesticides (Federal Insecticide, Fungicide, and Rodenticide Act) (#Chemical Profile for 2,4,5-T).

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Scientific Studies


Rotterdam Convention. Annex III. 2,4,5-T and its salts and esters. Accessed 3/10/2011.

IPCS International Programme on Chemical Safety. Chemical Safety Information from Intergovernmental Organizations. 2,4,5-T

International Chemical Safety Cards. (2,4,5-TRICHLOROPHENOXY) ACETIC ACID. Accessed 3/10/2011.

Pesticide Action Network North America (PANNA). Pesticides Database-Chemicals. 2,4,5-T. Accessed 3/10/2011.

Chemical Profile for 2,4,5-T. Scoredcard. The pollution information site. Accessed 3/10/2011.

Center for Disease Control and Prenvention (CDC). National Report on Human Exposure to Environmental Chemicals. 2,4,5-Trichlorophenoxyacetic Acid. Accessed 3/11/2011.

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