By: Grant Becker Will Mohle &

Characteristics  Thallium is extremely soft and malleable and can be cut with a knife at room temperature.  It has a metallic luster, but when exposed to air, it quickly tarnishes with a bluish-gray tinge that resembles lead. In the presence of water, thallium hydroxide is formed.

Detection  Acute thallium poisoning is primarily characterized by gastrointestinal symptoms, while neurologic findings predominate with chronic exposure.  Thallium toxicity is characterized by a painful ascending peripheral neuropathy and alopecia; this clinical manifestation presents 2-3 weeks after an acute poisoning.  Diplopia, abnormal color vision, impairment of visual acuity, hair loss, and dermatologic symptoms are also signs of thallium poisoning.

Cure  If exposure to thallium should exceed 0.1 mg per m 2 of skin in an 8-hour time-weighted average (40-hour work week) seek Prussian Blue, a dark blue pigment.

Lasting Effects  Lasting effects may include  neurologic manifestations such as: anxiety, confusion, delirium, hallucinations, psychosis, personality changes, depression, apathy, and confabulation.

History  The two chemists, William Crookes and Claude- Auguste Lamy, discovered thallium independently in 1861 by the newly developed method of flame spectroscopy. Both discovered the new element in residues of the sulfuric acid production.  Thallium is highly toxic and was used in ra poisons and insecticides.  Because of its use for murder, thallium has gained the nicknames "The Poisoner's Poison" and "Inheritance Powder"

Case Study 1  Nikolai Evgenievich Khokhlov (Николай Евгеньевич Хохлов) was a KGB officer who defected to the United States in In 1957 he testified about KGB activities. The KGB tried to kill him unsuccessfully using thallium. 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.

Case Study 2  In 1953, Australian Caroline Grills was 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. She became affectionately known as "Auntie Thally" to other inmates of Sydney's Long Bay prison.

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