EDTA

Ethylenediaminetetraacetic acid, widely abbreviated as EDTA (for other names, see Table), is a <a href="http://en.wikipedia.org/wiki/Polyamino_carboxylic_acid" title="Polyamino carboxylic acid" >polyamino carboxylic acid</a> and a colourless, water-soluble solid. Its <a href="http://en.wikipedia.org/wiki/Conjugate_base" title="Conjugate base" class="mw-redirect" >conjugate base</a> is named ethylenediaminetetraacetate. It is widely used to dissolve <a href="http://en.wikipedia.org/wiki/Limescale" title="Limescale" >limescale</a>. Its usefulness arises because of its role as a hexadentate ("six-toothed") <a href="http://en.wikipedia.org/wiki/Ligand" title="Ligand" >ligand</a> and <a href="http://en.wikipedia.org/wiki/Chelating_agent" title="Chelating agent" class="mw-redirect" >chelating agent</a>, i.e. its ability to "sequester" <a href="http://en.wikipedia.org/wiki/Metal" title="Metal" >metal</a><a href="http://en.wikipedia.org/wiki/Ion" title="Ion" >ions</a> such as Ca2+ and Fe3+. After being bound by EDTA, metal ions remain in solution but exhibit diminished reactivity. EDTA is produced as several salts, notably disodium EDTA and calcium disodium EDTA.

In <a href="http://en.wikipedia.org/wiki/Soft_drink" title="Soft drink" >soft drinks</a> containing <a href="http://en.wikipedia.org/wiki/Ascorbic_acid" title="Ascorbic acid" >ascorbic acid</a> and <a href="http://en.wikipedia.org/wiki/Sodium_benzoate" title="Sodium benzoate" >sodium benzoate</a>, EDTA mitigates formation of <a href="http://en.wikipedia.org/wiki/Benzene" title="Benzene" >benzene</a> (a <a href="http://en.wikipedia.org/wiki/Carcinogen" title="Carcinogen" >carcinogen</a>).<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-10" >[11]</a>

EDTA is used to bind metal ions in the practice of <a href="http://en.wikipedia.org/wiki/Chelation_therapy" title="Chelation therapy" >chelation therapy</a>, e.g., for treating <a href="http://en.wikipedia.org/wiki/Mercury_poisoning" title="Mercury poisoning" >mercury</a> and <a href="http://en.wikipedia.org/wiki/Lead_poisoning" title="Lead poisoning" >lead poisoning</a>.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-11" >[12]</a> It is used in a similar manner to remove excess iron from the body. This therapy is used to treat the complication of repeated blood transfusions, as would be applied to treat <a href="http://en.wikipedia.org/wiki/Thalassaemia" title="Thalassaemia" class="mw-redirect" >thalassaemia</a>.

Alternative medical practitioners believe EDTA acts as a powerful <a href="http://en.wikipedia.org/wiki/Antioxidant" title="Antioxidant" >antioxidant</a> to prevent free radicals from injuring blood vessel walls, therefore reducing <a href="http://en.wikipedia.org/wiki/Atherosclerosis" title="Atherosclerosis" >atherosclerosis</a>.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-12" >[13]</a> The <a href="http://en.wikipedia.org/wiki/Food_and_Drug_Administration" title="Food and Drug Administration" >U.S. FDA</a> approved the use of EDTA for lead poisoning<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-13" >[14]</a> on July 16, 1953, under the brand name of Versenate<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-14" >[15]</a>, which was licensed to the pharmaceutical company Riker. It has not approved it for the treatment of atherosclerosis.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-15" >[16]</a>

<a href="http://en.wikipedia.org/wiki/Dentist" title="Dentist" >Dentists</a> and <a href="http://en.wikipedia.org/wiki/Endodontist" title="Endodontist" class="mw-redirect" >endodontists</a> use EDTA solutions to remove inorganic debris (smear layer) and lubricate the canals in endodontics. This procedure helps prepare root canals for obturation. Furthermore, EDTA solutions with the addition of a surfactant loosen up calcifications inside a root canal and allow instrumentation (canals shaping) and facilitate apical advancement of a file in a tight/calcified root canal towards the apex. It serves as a preservative (usually to enhance the action of another preservative such as <a href="http://en.wikipedia.org/wiki/Benzalkonium_chloride" title="Benzalkonium chloride" >benzalkonium chloride</a>or <a href="http://en.wikipedia.org/wiki/Thiomersal" title="Thiomersal" >thiomersal</a>) in ocular preparations and eyedrops.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-16" >[17]</a> In evaluating <a href="http://en.wikipedia.org/wiki/Kidney_function" title="Kidney function" class="mw-redirect" >kidney function</a>, the complex [Cr(edta)]- is administered intravenously and its filtration into the urine is monitored. This method is useful for evaluating <a href="http://en.wikipedia.org/wiki/Glomerular_filtration_rate" title="Glomerular filtration rate" class="mw-redirect" >glomerular filtration rate</a>.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-17" >[18]</a>

EDTA is used extensively in the analysis of blood. It is an <a href="http://en.wikipedia.org/wiki/Anticoagulant" title="Anticoagulant" >anticoagulant</a> for blood samples for <a href="http://en.wikipedia.org/wiki/Complete_blood_count" title="Complete blood count" >CBC/FBEs</a>.

Laboratory studies also suggest that EDTA chelation may prevent collection of platelets on the lining of the vessel [such as arteries] (which can otherwise lead to formation of blood clots, which itself is associated with atheromatous plaque formation or rupture, and thereby ultimately disrupts blood flow). These ideas have so far been proven ineffective;<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-18" >[19]</a>however, a major clinical study of the effects of EDTA on coronary arteries is currently (2008) proceeding.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-clinical_study-19" >[20]</a> EDTA played a role in the <a href="http://en.wikipedia.org/wiki/O.J._Simpson_murder_case" title="O.J. Simpson murder case" class="mw-redirect" >O.J. Simpson trial</a> when the defense alleged that one of the blood samples collected from Simpson's estate was found to contain traces of the compound.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-20" >[21]</a>

EDTA is a slime dispersant, and has been found to be highly effective in reducing bacterial growth during implantation of <a href="http://en.wikipedia.org/wiki/Intraocular_lenses" title="Intraocular lenses" class="mw-redirect" >intraocular lenses</a> (IOLs).<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-21" >[22]</a>

EDTA is in such widespread use that it has emerged as a <a href="http://en.wikipedia.org/wiki/Persistent_organic_pollutant" title="Persistent organic pollutant" >persistent organic pollutant</a>.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-23" >[24]</a> It degrades to ethylenediaminetriacetic acid, which then cyclizes to the <a href="http://en.wikipedia.org/wiki/Diketopiperazine" title="Diketopiperazine" >diketopiperizide</a>, a cumulative, persistent, organic environmental pollutant. An alternative chelating agent with fewer environmental pollution implications is <a href="http://en.wikipedia.org/wiki/Ethylenediamine-N,N%27-disuccinic_acid" title="Ethylenediamine-N,N'-disuccinic acid" class="mw-redirect" >EDDS</a>.

EDTA exhibits low acute toxicity with <a href="http://en.wikipedia.org/wiki/Median_lethal_dose" title="Median lethal dose" >LD50</a> (rat) of 2.0 – 2.2 g/kg.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-Ullmann-3" >[4]</a> It has been found to be both <a href="http://en.wikipedia.org/wiki/Cytotoxicity" title="Cytotoxicity" >cytotoxic</a> and weakly <a href="http://en.wikipedia.org/wiki/Genotoxicity" title="Genotoxicity" >genotoxic</a> in laboratory animals. Oral exposures have been noted to cause reproductive and developmental effects.<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-lanigan2002-9" >[10]</a> The same study by Lanigan<a href="http://en.wikipedia.org/wiki/EDTA#cite_note-lanigan2002-9" >[10]</a> also found that both dermal exposure to EDTA in most cosmetic formulations and inhalation exposure to EDTA in aerosolized cosmetic formulations would produce exposure levels below those seen to be toxic in oral dosing studies.

EDTA

Attachments