2, 4, 5-trichlorophenoxy acetic acid

IUPAC name:2,4,5-trichlorophenoxy acetic acid
ISO name (common): 2,4,5-T
Molecular Formula:C₈H₅Cl₃O₃
Structural Formula:

     Cl        H
       \      /
        C == C     H OH
       /      \    | |  
   Cl-C        C-O-C-C=O
       \\    //    |
        C -- C     H
       /      \
      H       Cl

Rat LD50_oral: 500mg/kg
Rat LD50_dermal: >5000mg/kg
Rat LD50_inhalation: 0.83mg/l (4 hour exposure)

Carcinogenicity: No evidence of carcinogenic properties in humans
Neurotoxicity: Neurotoxic at high concentrations (reversible)

2,4,5-T considerably irritates the eyes, and the skin. Skin resorption is likely. Chronic exposure causes impairment of the liver function, changes in behaviour and nerve damage. If ingested 2,4,5-T can cause diarrhoea, drowsiness, headache, nausea, unconsciousness, and vomiting.

2,4,5-T has been found to be slightly teratogenic, although only when contaminated by 2,3,7,8-tetrachloro-dibenzo-para-dioxin (TCDD) which is an unfortunate by-product of 2,4,5-T's manufacture.

2,4,5-T, like 2,4-D, is a selective herbicide. Used widely during the conflict in Vietnam by the US as a defoliant. It was mixed in a 50:50 ratio with 2,4-D to produce Agent Orange, produced for the US military by Monsanto.

However, the use of 2,4,5-T as an agricultural herbicide has been banned since 1970 in Italy, Holland, Sweden and Norway and since 1985 in the US.

Development of bioremediation techniques including the refinement of Burkholderia cepacia strain H1 are ongoing. The aim is to be able to remove 2,4,5-T from contaminated water and soil.

Documentation on monitoring and evaluating environmental impacts - German Federal Ministry for Economic Cooperation and Development Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung (BMZ)
International Chemical Safety Cards #0075 - IPCS
Agent Orange: The Poisoning of Vietnam - The Ecologist 28:5 1998