804 2,4,5-Trichlorophenoxyacetic acid 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 and was widely used in the agricultural industry until being phased out, starting in the late 1970s due to toxicity concerns. 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. IARC considers the chlorophenoxyacetic acids group of chemicals as possibly carcinogenic to humans. 93-76-5 1480 C8H5Cl3O3 253.930430 White powder. 153°C 0.278 mg/mL at 25°C [HARTLEY,D & KIDD,H (1983)] CDDs cause their toxic effects by binding to the aryl hydrocarbon receptor and subsequently altering the trascription of certain genes. The affinity for the Ah receptor depends on the structure of the specific CDD. The change in gene expression may result from the direct interaction of the Ah receptor and its heterodimer-forming partner, the aryl hydrocarbon receptor nuclear translocator, with gene regulatory elements or the initiation of a phosphorylation/dephosphorylation cascade that subsequently activates other transcription factors. The affected genes include several oncogenes, growth factors, receptors, hormones, and drug-metabolizing enzymes. The change in transcription/translation of these genes is believed to be the cause of most of the toxic effects of CDDs. This includes 2,3,7,8-tetrachlorodibenzo-p-dioxin's carcinogenicity is thought to be the result of its ability to alter the capacity of both exogenous and endogenous substances to damage the DNA by inducing CYP1A1- and CYP1A2-dependent drug-metabolizing enzymes. (L177) CDDs are absorbed through oral, inhalation, and dermal routes of exposure. CDDs are carried in the plasma by serum lipids and lipoproteins, distributing mainly to the liver and adipose tissue. CDDs are very slowly metabolized by the microsomal monooxygenase system to polar metabolites that can undergo conjugation with glucuronic acid and glutathione. They may increase the rate of their own metabolism by inducing CDDs induce both phase I and phase II enzymes. The major routes of excretion of CDDs are the bile and the feces, though smaller amounts are excreted in the urine and via lactation. (L177) 2B, possibly carcinogenic to humans. (L135) Dioxins occur as by-products from the manufacture of organochlorides, the bleaching of paper, chlorination by waste and drinking water treatment plants, municipal solid waste and industrial incinerators, and natural sources such as volcanoes and forest fires. (L177, L178) Exposure to large amounts of CDDs causes chloracne, a severe skin disease with acne-like lesions that occur mainly on the face and upper body. CDDs may also cause liver damage and induce long-term alterations in glucose metabolism and subtle changes in hormonal levels. In addition, studies have shown that CDDs may disrupt the endocrine system and weaken the immune system, as well as cause reproductive damage and birth defects, central and peripheral nervous system pathology, thyroid disorders, endometriosis, and diabetes. 2,3,7,8-Tetrachlorodibenzo-p-dioxin is also a known human carcinogen. (L177, L178) In addition to chloracne, CDD exposure causes skin rashes, discoloration, and excessive body hair. (L177) Treatment may include washing any areas of contact, GI decontamination if swallowed, administering an IV and forced alkaline diuresis. (L346) 2009-06-02T22:20:30Z 2014-12-24T20:22:50Z C07100 27903 CPD-121 D015085 2,4,5-Trichlorophenoxyacetic acid 1419 true OC(=O)COC1=CC(Cl)=C(Cl)C=C1Cl C8H5Cl3O3 InChI=1S/C8H5Cl3O3/c9-4-1-6(11)7(2-5(4)10)14-3-8(12)13/h1-2H,3H2,(H,12,13) InChIKey=SMYMJHWAQXWPDB-UHFFFAOYSA-N 255.483 253.930427147 Exogenous Solid CHEMBL194458 1435