4029 Thallium Thallium is a chemical element with symbol Tl and atomic number 81. This soft gray post-transition metal is not found free in nature. When isolated, it resembles tin, but discolors when exposed to air. Thallium tends to oxidize to the +3 and +1 oxidation states as ionic salts. The +3 state resembles that of the other elements in thallium's group (boron, aluminum, gallium, indium). However, the +1 state, which is far more prominent in thallium than the elements above it, recalls the chemistry of alkali metals, and thallium(I) ions are found geologically mostly in potassium-based ores, and (when ingested) are handled in many ways like potassium ions (K+) by ion pumps in living cells. Thallium and its compounds are extremely toxic, and should be handled with great care. There are numerous recorded cases of fatal thallium poisoning. Contact with skin is dangerous, and adequate ventilation should be provided when melting this metal. 7440-28-0 24642 Tl 204.383 Silvery white solid. 303.5°C 1473 °C Thallium(I) compounds have a high aqueous solubility. Dermal; inhalation; ingestion Thallium(I) compounds have a high aqueous solubility and are readily absorbed through the skin. 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 metal cations, particularly potassium (due to similar atomic radii). It can thus enter the body via potassium uptake pathways. Other aspects of thallium's chemistry differ strongly from that of the alkali metals, such its high affinity for sulfur ligands. Thus this substitution disrupts many cellular processes (for instance, thallium may attack sulfur-containing proteins such as cysteine residues and ferredoxins). (Wikipedia) A 2013 study found evidence that the thallium(I)-induced liver toxicity is a result of the disruptive effect of this metal on the mitochondrial respiratory complexes (I, II, and IV), which are the obvious causes of metal-induced reactive oxygen species formation and ATP depletion. The latter two events, in turn, trigger cell death signaling via opening of mitochondrial permeability transition pore and cytochrome c expulsion. (A15464) Thallium is rapidly distributed throughout all tissues of the body. Most thallium is excreted by the faecal route but up to 35% may be excreted by the kidneys. (L2148) The lethal dose is around 15 to 20 mg per kg body weight but serious toxicity and even death can occur with rather less. (L2148) No indication of carcinogenicity to humans (not listed by IARC). Thallium(I) ions are found geologically mostly in potassium-based ores. Commercially, however, thallium is produced not from potassium ores, but as a byproduct from refining of heavy metal sulfide ores. Approximately 60–70% of thallium production is used in the electronics industry, and the remainder is used in the pharmaceutical industry and in glass manufacturing. It is also used in infrared detectors. The radioisotope thallium-201 (as the soluble chloride TlCl) is used in small, nontoxic amounts as an agent in a nuclear medicine scan, during one type of nuclear cardiac stress test. Soluble thallium salts were historically used in rat poisons and insecticides. Because of its historic popularity as a murder weapon, thallium has gained notoriety as "the poisoner's poison" and "inheritance powder" (alongside arsenic). (Wikipedia) Among the distinctive effects of thallium poisoning are loss of hair (which led to its initial use as a depilatory before its toxicity was properly appreciated) and damage to peripheral nerves (victims may experience a sensation of walking on hot coals), although the loss of hair only generally occurs in low doses; in high doses the thallium kills before this can take effect. (Wikipedia) Thallium toxicity is complex and severe. It affects several systems in human body, including liver, gastrointestinal, cardiovascular, reproductive, renal, and nervous systems. Among them, liver is an important organ which possibly assists metabolic reduction of metals; hence, it could be a noticeable organ for thallium toxicity. This is confirmed by the other study on thallium-induced toxicity in experimental animals which reported highest accumulation in liver, kidney, and ileum. (A15464) Nausea and vomiting; painful peripheral neuropathy; alopecia. (L2148) One of the main methods of removing thallium (both radioactive and normal) from humans is to use Prussian blue, which is a material which absorbs thallium. Up to 20 g per day of Prussian blue is fed by mouth to the person, and it passes through their digestive system and comes out in the stool. Hemodialysis and hemoperfusion are also used to remove thallium from the blood serum. At later stage of the treatment additional potassium is used to mobilize thallium from the tissue. 2014-08-29T04:48:24Z 2026-04-17T18:58:36Z Thallium C15226 37117 true [Tl+] Tl InChI=1S/Tl/q+1 ZLUSCZLCHQSJRU-UHFFFAOYSA-N 204.3833 204.97441227 Exogenous Solid HMDB13724 23044 CHEM002935 DTXSID2036035 NS00099728 λ¹-thallanylium