Thallium (pronEng|ˈθæliəm) is a
chemical elementwith the symbol Tl and atomic number81. [ [http://periodic.lanl.gov/elements/81.html "thallium"] , Los Alamos National Laboratory. Retrieved November 21, 2006.] This soft gray malleable poor metalresembles tinbut discolors when exposed to air. Approximately 60-70% of thallium production is used in the electronics industry, and the rest is used in the pharmaceutical industryand in glass manufacturing. It is also used in infrared detectors.cite web
url = http://adsabs.harvard.edu/abs/1977ApOpt..16.2942N
title = Thallium selenide infrared detector
accessdate = 2006-11-25
author = Nayer, P. S
coauthors = Hamilton, O.
publisher = Smithsonian/NASA ADS Physics Abstract Service
quote = Thallium is highly
toxicand is used in rat poisons and insecticides, and its use has been cut back or eliminated in many countries. It is used in murdersand has the nicknames "The Poisoner's Poison" and "Inheritance powder" (alongside arsenic).
Thallium is very soft and malleable and can be cut with a knife. It has a metallic
luster, but when exposed to air, it quickly tarnishes with a bluish-grey tinge that resembles lead. (It is preserved by keeping it under oil). A heavy layer of oxidebuilds up on thallium if left in air. In the presence of water, thallium hydroxideis formed.
Occurrence and production
Thallium occurs naturally in the minerals
crookesite, lorandite, hutchinsonite, and pyrite.cite web|title=Chemical fact sheet — Thallium | publisher="Spectrum Laboratories" | year=2001 | month=April | url=http://www.speclab.com/elements/thallium.htm | accessdate=2008-02-02]
odorless and tasteless thallium sulfate was once widely used as rat poisonand antkiller. Since 1975, this use in the United Statesand many other countries is prohibited due to safety concerns. Other uses:
thallium sulfide's electrical conductivitychanges with exposure to infrared lighttherefore making this compound useful in photocells.
*Thallium(III) salts, as thallium trinitrate or triacetate, are useful reagents in organic synthesis performing different transformations in aromatics, ketones, olefins, among others.
bromide- iodide crystals have been used as infrared optical materials, because they are harder than other common infrared optics, and because they have transmission at significantly longer wavelengths. The trade name KRS-5 refers to this material.
thallium oxidehas been used to manufacture glasses that have a high index of refraction.
semiconductormaterials for selenium rectifiers,
*used as a
dopantfor sodium iodidecrystals in gamma radiationdetection equipment, such as scintillation counters,
*high-density liquid used for sink-float separation of
*used in the treatment of
ringwormand other skin infections. However this use has been limited due to the narrow therapeutic index.
radioactivethallium-201 (half-life of 73 hours) is used for diagnostic purposes in nuclear medicine, particularly in stress tests used for risk stratification in patients with coronary artery diseaseA(CAD). [ [http://www.wramc.amedd.army.mil/departments/nuclear/PatientInfo/Thallium.htm Thallium Test] from Walter Reed Army Medical Center] [ [http://www.americanheart.org/presenter.jhtml?identifier=4743 Thallium Stress Test] from the American Heart Association] This isotope of thallium can be generated using a transportable generator which is similar to the technetium cow. [ [http://www.medscape.com/medline/abstract/7169272 Abstract] ] The generator contains lead-201 (half life 9.33 hours) which decays by electron captureto the thallium-201. The lead-201 can be produced in a cyclotronby the bombardment of thallium with protons or deuterons by the (p,3n) and (d,4n) reactions. [ [http://www.med.harvard.edu/JPNM/physics/isotopes/Tl/Tl201/prod.html Thallium-201 production] from Harvard Medical School's Joint Program in Nuclear Medicine]
sulfuror seleniumand arsenic, thallium has been used in the production of high- densityglasses that have low melting points in the range of 125 and 150 °C. These glasses have room temperature properties that are similar to ordinary glasses and are durable, insoluble in water and have unique refractive indices.
*an 8.5% thallium amalgam is used in thermometers and switches for use in low temperatures, because it freezes at -58 °C (pure mercury freezes at -38 °C).
*thallium is used in the electrodes in dissolved oxygen analyzers.
*thallium is a constituent of the alloy in the anode plates in magnesium seawater batteries.
In addition, research activity with thallium is ongoing to develop high-temperature superconducting materials for such applications as
magnetic resonance imaging, storage of magnetic energy, magnetic propulsion, and electric power generationand transmission.
Thallium (Greek "θαλλός", "thallos", meaning "a green shoot or twig") [Liddell & Scott, " [http://perseus.mpiwg-berlin.mpg.de/cgi-bin/resolveform?doc=Perseus%3Atext%3A1999.04.0057;layout=;query=toc;loc=qallo%2Fs A Greek-English Lexicon] ", "sub" " [http://perseus.mpiwg-berlin.mpg.de/cgi-bin/resolveform?lookup=qallos&type=begin&lang=greek&searchText=&options=Sort+Results+Alphabetically&.submit=Submit&formentry=1&lang=greek θαλλος] "] was discovered by
Sir William Crookesin 1861in Englandwhile he was making spectroscopic determinations for telluriumon residues from a sulfuric acidplant. The name comes from Thallium's bright greenspectral emission lines. In 1862 Crookes and Claude-Auguste Lamyisolated the metal independently of each other.
Although the metal is reasonably abundant in the
Earth's crust at a concentration estimated to be about 0.7 mg/kg, mostly in association with potassiumminerals in clays, soils, and granites, it is not generally considered to be commercially recoverable from those forms. The major source of commercial thallium is the trace amounts found in copper, lead, zinc, and other sulfide ores.
Thallium is found in the minerals
crookesiteTlCu7Se4, hutchinsoniteTlPbAs5S9, and loranditeTlAsS2. It also occurs as trace in pyriteand extracted as a by-product of roasting this ore for sulfuric acid production. The metal can be obtained from the smeltingof lead and zinc rich ores. Manganese nodules found on the ocean flooralso contain thallium, but nodule extraction is prohibitively expensive and potentially environmentally destructive. In addition, several other thallium minerals, containing 16% to 60% thallium, occur in nature as sulfide or selenide complexes with antimony, arsenic, copper, lead, and silver, but are rare, and have no commercial importance as sources of this element. See also: "."
Thallium has 25
isotopes which have atomic masses that range from 184 to 210. 203Tl and 205Tl are the only stable isotopes, and 204Tl is the most stable radioisotope, with a half-lifeof 3.78 years.
202Tl (half life 12.23 days) can be made in a cyclotron, [ [http://www.eh.doe.gov/ohre/roadmap/histories/0472/0472d.html Thallium Research] from Department of Energy] while 204Tl (half life 3.78 years) is made by the
neutron activationof stable thallium in a nuclear reactor. [ [http://www-pub.iaea.org/MTCD/publications/PDF/te_1340_web.pdf Manual for reactor produced radioisotopes] from the International Atomic Energy Agency]
Fluorides: TlF, TlF3
Chlorides: TlCl, TlCl2, TlCl3
Bromides: TlBr, Tl2Br4
Iodides: TlI, TlI3
Hydrides: none listed
Oxides: Tl2O, Tl2O3
Tellurides: none listed
Nitrides: none listed
Thallium and its compounds are very toxic, and should be handled with great care [http://www.webelements.com/webelements/elements/text/Tl/biol.html] . Contact with skin is dangerous, and adequate ventilation should be provided when melting this metal [http://www.webelements.com/webelements/elements/text/Tl/biol.htm] .Thallium(I) compounds have a high aqueous
solubilityand are readily absorbed through the skin. Exposure to them should not exceed 0.1 mg per m² of skin in an 8-hour time-weighted average (40-hour work week). Thallium is a suspected human carcinogen.
Part of the reason for thallium's high toxicity is that, when present in aqueous solution as the univalent thallium(I) ion (Tl+), it exhibits some similarities with essential
alkali metalcations, particularly potassium(as the atomic radius is almost identical). It can thus enter the body via potassium uptake pathways. However, other aspects of thallium's chemistry are very different from that of the alkali metals ("e.g.", its high affinity for sulfurligands due to the presence of empty d-orbitals), and so this substitution disrupts many cellular processes (for instance, thallium may attack sulfur-containing proteins such as cysteineresidues and ferredoxins).
Thallium's toxicity has led to its use (now discontinued in many countries) as a
Among the distinctive effects of thallium poisoning are loss of hair (which led it to its initial use as a
depilatorybefore its toxicity was properly appreciated) and damage to peripheral nerves (victims may experience a sensation of walking on hot coals). Thallium was once an effective murder weapon before its effects became understood, and an antidote ( prussian blue) discovered.
Treatment and internal decontamination
One of the main methods of removing thallium (both radioactive and normal) from humans is to use
Prussian blue, which is a solid ion exchangematerial which absorbs thallium and releases potassium. The prussian blue is fed by mouth to the person, and it passes through their digestive system and comes out in the stool. [ [http://www.bt.cdc.gov/radiation/prussianblue.asp Prussian blue fact sheet] from the Centers for Disease Control and Prevention]
Famous uses as a poison
* In 1953,
Australian Caroline Grillswas sentenced to life in prison after three family members and a close family friend died. Authorities found thallium in tea that she had given to two additional family members. [http://news.bbc.co.uk/1/hi/uk/6163520.stm "What is thallium?"] , BBC, November 19, 2006. Retrieved November 21, 2006.]
* In 1957,
Nikolai Khokhlov, a former KGBassassin, was poisoned with thallium.cite book | author= Christopher Andrewand Vasili Mitrokhin| title=The Mitrokhin Archive: The KGB in Europe and the West | publisher=Gardners Books | year=2000 | isbn=0-14-028487-7] Khokhlov fell ill with stomach cramps and nausea and within days his hair had fallen out and he was covered with marks on his skin. He fled the Soviet Union to Germany where doctors suspected thallium poisoning and tried every known antidote without success. Khokhlov was then taken to the US hospital and treated with hydrocortisone, steroids, and blood and plasma transfusions and he eventually recovered.
* In 1971, thallium was the main poison that
Graham Frederick Youngused to poison around 70 people in the English village of Bovingdon, Hertfordshire, of which 2 died.Fact|date=February 2008
Zhu Ling (1973)the victim of an unsolved 1995 thallium poisoning case in Beijing, China. In 1994, Zhu Ling was a sophomore in Class Wuhua2 (Physical Chemistry) at Tsinghua University in Beijing. She began to show strange and debilitating symptoms at the end of 1994, when she reported experiencing acute stomach pain, along with extensive hair loss. Ultimately she was diagnosed on Usenetwith poisoning by thallium. To this date speculation of the true poisoner is still discussed by many Chinese expatriates overseas
* In 1988, members of the Carr family from Alturas, Polk County, Florida fell ill from what appeared to be thallium poisoning. Peggy Carr, the mother, died slowly and painfully from the poison. Her son and stepson were critically ill but eventually recovered. The Carr's neighbor,
George J. Trepal, a chemist and member of Mensa, was convicted of murdering Mrs. Carr and attempting to murder her family and sentenced to death. The thallium was slipped into bottles of Coca-Cola at the Carr's home and Trepal's. [cite web|url=http://www.floridacapitalcases.state.fl.us/case_updates/121965.doc|title=The Case of TREPAL, George (W/M)|publisher=The Commission on Capital Cases|accessdate=2007-11-29]
* In June 2004, 25 Russian soldiers earned Honorable Mention
Darwin Awardsafter becoming ill from thallium exposure when they found a can of mysterious white powder in a rubbish dump on their base at Khabarovskin the Russian Far East. Oblivious to the danger of misusing an unidentified white powder from a military dump site, the conscripts added it to tobacco, and used it as a substitute for talcum powderon their feet. [ [http://darwinawards.com/stupid/stupid2004-16.html White Russians] at DarwinAwards.com]
* In 2005, a 17 year old girl in Numazu, Shizuoka,
Japan, admitted to attempting to murder her mother by lacing her tea with thallium, causing a national scandal. [ [http://www.gaijinpot.com/read_news.php?id=6623 "Girl admits trying to kill mom by lacing her tea"] , "GaijinPot", April 28, 2005. News Source from Mainichi Shimbun. Retrieved November 21, 2006.]
* In February 2007, two Americans, Marina and Yana Kovalevsky, a mother and daughter, visiting Russia were hospitalized due to thallium poisoning. Both had emigrated from the Soviet Union to the United States in 1989 and had made several trips to Russia since then. [ [http://www.foxnews.com/story/0,2933,257278,00.html "Embassy Confirms Hospitalization of Two Americans for Thallium Poisoning"] , Foxnews.com,
March 7, 2007. Retrieved March 7, 2007.]
* In February 2008, members of Iraqi air force club and some of their children were poisoned by cake laced with thallium. [ [http://news.bbc.co.uk/2/hi/middle_east/7237086.stm "Poison cake kills Iraqi children"] , news.bbc.co.uk,
February 9, 2008. Retrieved February 9, 2008.] Two of the children died.
Agatha Christie, who worked as a pharmacist, used thallium as the agent of murder in her detective fictionnovel "The Pale Horse" — the first clue to the murder method coming from the hair loss of the victims. This novel is notable as being credited with having saved at least two lives after readers recognised the symptoms of thallium poisoning that Christie described. [http://www.bmj.com/cgi/content/full/334/7586/205?rss=1]
* In Nigel Williams' 1990 novel "
The Wimbledon Poisoner", Henry Far uses thallium to bastea roast chicken in a failed attempt to murder his wife.
* Thallium figures prominently in the 1995 film "
The Young Poisoner's Handbook", a dark comedy loosely based on the life of Graham Frederick Young.
* "Concentrated thallium" is used as the poison of choice of the Wyoming Widow in the 2006 dark comedy "
* In an episode of the TV show House, a doctor poisons a patient with Thallium to make it appear that she had
Larry Niven's Known Spacecycle of science fiction stories, Thallium is a soil component essential for the proper growth of Tree of lifewhich, when ingested by hominid species, triggers the change from the Breeder lifestage to the "Protector" lifestage.
* In the "Page Turner" episode of , Thallium 201 is used to poison several individuals.
* [http://www.webelements.com/webelements/elements/text/Tl/index.html WebElements.com — Thallium]
* [http://www.emedicine.com/emerg/topic926.htm Toxicity, Thallium]
* [http://www.timesonline.co.uk/article/0,,251-2461655,00.html Slow-acting killer that was Saddam's favourite instrument of vengeance]
* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+thallium,+elemental NLM Hazardous Substances Databank – Thallium, Elemental]
* [http://www.crimelibrary.com/criminal_mind/forensics/cyril_wecht/7.html Cyril Wecht, Thallium, Robert Curley]
* [http://www.atsdr.cdc.gov/tfacts54.html ATSDR - ToxFAQs]
* [http://www.guardian.co.uk/Iraq/Story/0,,2254956,00.html The Guardian reports: Two Iraqi children die from Thallium poisoning: 9 February 2008]
* [http://www.pse-mendelejew.de/bilder/tl.jpgpure Thallium >=99,99% picture in the element collection from Heinrich Pniok]
* [http://www.smart-elements.com/?arg=zoom&element=Tl&art=1967&newitems=&ref=Tl&seite=0&total=1&suche=#magnify pure Thallium casted in acrylic for safe handling]
Wikimedia Foundation. 2010.