Cloud man earlier this year has a deadly legacy, tied to assassinations, mass poisonings and Cold War-era plots. Today, thallium is used in manufacturing electronics, semiconductors, specialty glass, and in some medical imaging. After it was published, a British man, Graham Young, known as “The Teacup Poisoner,” used thallium to murder at least three people and poison more than 70 others. During the Rhodesian Bush War, the substance was used as a weapon, according to the National Defense University Press. The thallium sulfate photo used in this story was published according to the CC BY-SA 4.0 license.