Thallium, the Cursed Element

Back in 1978, John Emsley, a British chemistry professor and science writer, summed up the case against thallium, a heavy metal that is one of chemistry’s basic elements, for The New Scientist. “If ever an element was cursed at birth, that element was thallium,” he wrote. The mystery writer Agatha Christie also knew a thing or two about thallium, which starred in her 1961 thriller, The Pale Horse. (You can learn about that and much more in a podcast transcript by the Royal Society of Chemistry’s magazine, Chemistry World.)

All in all, despite internet claims to the contrary, there is no shortage of material on thallium. Numerous academic journals, textbooks, and public information sources explain the various ways thallium can be harmful to humans, as well as the difficulties of monitoring and understanding it. What follows is an abridged collection of the scientific literature used by Ernie Hubbard and Dr. Michael Rosenbaum to understand how thallium functions in soil, water, and air; in plants and animals, and in the human body. Hubbard and Rosenbaum drew on more than a dozen other sources, but these are the references that are most relevant to our article, and seem most accessible to readers. Where online links are provided, you can click and read more (though you may need to Google some of the terms bandied about by toxicologists and chemists).

ACADEMIC RESEARCH ABOUT THE TOXICITY OF THALLIUM

This 1978 article in the Journal of Toxocological Sciences provides a rather graphic account of acute thallotoxicosis, based on an autopsy of a 22 year-old Japanese man who mixed thallous sulfide from rat poison with alcohol and committed suicide.

“Thallium salts are highly poisonous to human organisms,” reports this study, The Group 13 Metals Aluminium, Gallium, Indium and Thallium, edited by two UK chemists and published in 2011. You can read excerpts on Google Books.

A 2003 reference work on poisons, Emergency Toxicology, reviews thallium’s symptoms. You can read excerpts on Google Books.

Greenberg’s Text-Atlas of Emergency Medicine, compiled by a team of emergency medicine specialists and published in 2004 by Wolters Kluwer, documents connections between thallium and alopecia and peripheral neuropathy.

The Encyclopedia of Toxicology also notes the common symptoms of alopecia and peripheral neuropathy. See an excerpt on Google Books.

As does a textbook on clinical neurotoxicology, also on Google Books.

A work by Andrew Hall Cutler, Hair Test Interpretation: Finding Hidden Toxicities, notes the difficulty of accurately testing thallium samples. You can read an excerpt on Google Books.

A study of metallic carcinogenicity by a U.K. chemist notes the usefulness of testing hair for thallium’s presence. You can read an excerpt on Google Books.

Another study titled “Instrumental Methods in Metal Ion Speciation” notes thallium’s possible interactions in body chemistry, which aren’t completely understood. (Note that for chemists, “speciation” refers to analyzing the presence of various elements in the world around us.) You can read an excerpt on Google Books.

This 2005 work about chemical speciation also examines the presence of thallium in humans, and highlights risks during pregnancy. You can read an excerpt on Google Books.

A 2008 study by chemists at the University of Kashmir looks at how interactions with other chemicals may affect the toxicity of thallium. You can download the article.

This 1967 study by two University of Minnesota veterinary medicine professors examines relationships between potassium and thallium in animals, finding that potassium may help clear thallium from their bodies.

In this 1978 study published by Molecular Nutrition and Food Research, B. Venugopal and T.D. Luckey explored “Metal toxicity in mammals.” You can purchase the article here.

THALLIUM AND FOOD

A study by Czech Republic agricultural researchers in 2006 investigated kale’s uptake of thallium from soils with a naturally high amount of the element, and concluded it could seriously endanger the food chain.

A Chilean study published in 2009 examines the presence of thallium in potatoes grown in the northern region of the country, and finds an “important risk.”

A Canadian review in 2004 by researchers at the University of Regina, Saskatchewan (which is no longer available online), noted thallium “can be transferred from soils to crops readily and accrues in fuel crops.”

A study published in a Polish journal in 2009 by Slovakian researchers at Comenius University in Bratislava (no longer online) examines the effect of thallium accumulation on fungal growth.

A 2008 report from the U.S. Centers for Disease Control, cited by SafetyLit.org, documents a case of an Iraqi family poisoned by eating thallium-contaminated cake. A BBC News account of the “mysterious” case noted it was the first instance since Saddam Hussein’s reign; the dictator was known to use thallium against his opponents.

Researchers at the New York City Poison Center in 1994 documented a case of thallium poisoning of children who ate contaminated candy.

PUBLIC-SECTOR AND REFERENCE SOURCES

This “Frequently Asked Questions” page from the Agency for Toxic Substances and Disease Registry, an arm of the Centers for Disease Control and Prevention, offers a clear overview of what’s known about thallium risks.

You can also read a more thorough review of thallium’s presence and potential for human exposure from the Agency.

This page from the CDC reviews what’s known about dangerous levels of the metal.

This “toxicological profile” was prepared by a private company for the federal government in 1992, and notes that there is little information about the “distribution” of thallium in humans.

This 2007 study for the U.S. Army looks at thallium toxicity in wildlife.

This page from a California state agency covers some of the same information as the CDC documents.

The U.S. Food and Drug Administration’s regulations on reviewing food additives are here.

The United Nations World Health Organization published a health and safety guide to thallium in 1996.

And Medscape, an online reference source, offers a well-organized overview of the history of thallium’s use and effects.