Thallium (Tl)
Definition
The 'poisoner's poison' because thallium sulphate is tasteless, odourless and colourless. Substitutes for potassium in cellular transport. Alopecia at 2 to 3 weeks is pathognomonic. Historically used in rodenticides and depilatory creams; banned in most countries.
- Common name
- The poisoner's poison
- Detection difficulty
- Tasteless, odourless, colourless
- Mechanism
- Substitutes for potassium in cellular transport
- Pathognomonic sign
- Alopecia at 2 to 3 weeks
- Historical use
- Rodenticides and depilatory creams, now banned
Common questions
Why is thallium poisoning easy to miss early on?+
Because it is undetectable by taste or smell and its early symptoms, such as gastrointestinal upset and nerve pain, resemble many common illnesses, poisoning is often mistaken for a viral or gastrointestinal condition until the delayed hair loss appears.
How does thallium's mechanism explain its toxicity?+
Because thallium closely mimics potassium, cells take it up through the same transport pathways and incorporate it into processes that depend on potassium, disrupting nerve conduction and enzyme function throughout the body rather than attacking a single organ.
Related terms
- Arsenic (As)
- Metalloid; trivalent arsenite (As III) is 60 times more toxic than pentavalent arsenate (As V). Thiol-group blocker that poisons mitochondrial enzymes (pyruvate...
- Dry Ashing
- Viscera or hair is dried and incinerated in a muffle furnace at 450 to 550 degrees Celsius. Inorganic ash is dissolved in...
- Hydride Generation (HG-AAS)
- Sensitivity booster for As, Sb and Se. Sample plus NaBH4 in acid liberates AsH3 / SbH3 / SeH2 gas, which is swept...
- Lead (Pb)
- Cumulative neurotoxin from chronic occupational exposure (battery recycling, smelter work), leaded paint, contaminated cosmetics (low-grade sindoor, surma, kohl), and adulterated Ayurvedic preparations....
- Marsh Test (1836)
- Confirmatory test for arsenic devised by James Marsh after the Bodle case (1832), in which Marsh was unable to convince a jury...
- Mercury (Hg)
- Three toxic forms: elemental (vapour from broken thermometers, dental amalgam), inorganic salts (mercuric chloride, corrosive sublimate), and organic (methylmercury from biomagnification, ethylmercury...
- Reinsch Test
- Classical screen for arsenic, antimony, mercury and bismuth. A clean copper strip is immersed in the acidified sample (concentrated HCl, near-boiling) for...
- Wet Digestion
- Viscera is digested with HNO3 + H2SO4 + HClO4 (or HNO3 + H2O2) at controlled temperature. Closed-vessel microwave-assisted digestion in Teflon bombs...