Transcription
Translator: Hani Eldalees
From 1952 to 1953, Sydney detectives investigated a staggering number of murders and attempted murders that were unrelated but shared a common element: thallium poisoning. The secret to thallium's toxicity lies in its structural similarity to potassium – an element that helps regulate body fluids, initiate muscle contractions, and transmit nerve signals. Even if a small amount of thallium sneaks into the body – for example, via contaminated tea or a slice of cake – it easily replaces potassium, causing the body to slowly and painfully shut down.
At the time, the dangers of thallium were well known, so how did perpetrators manage to get their hands on such a deadly element? And thallium is not the only dangerous element on the periodic table. Within this tabular grouping loom many potential threats, each with its own unique method of inflicting destruction. Some elements, like thallium, are dangerous because of their toxicity. Once they enter the body, they wreak havoc on the biological systems that keep us alive. Lead, for example, displaces essential body metals like calcium, which in turn disrupts nerve communication in the brain. It travels through the bloodstream, also generating toxic levels of molecules known as reactive oxygen species, and can stress and kill cells.
Mercury’s toxicity became infamous in the 19th century due to its widespread use in the production of felt hats. Prolonged exposure caused hat makers to develop what was later known as “mad hatter” disease, with symptoms including personality changes, emotional disturbances, and tremors. Mercury quickly reacts with specific parts of proteins throughout the body. When bound, mercury transforms proteins into different shapes, rendering them useless.
Some elements are dangerous because of how they react, interact, or even explode in the external environment. The highly reactive elements are found in the first column of the periodic table and are known as alkali metals. Rarely found in their pure elemental form, alkalis readily donate the single electron in their outer shell to anything available to form more stable ionic compounds. This can lead to violent results – pure cesium, for example, explodes when exposed to air and detonates when dropped in water. Francium is likely the most reactive alkali based on its position on the periodic table, but we don’t know for sure. With a half-life of 22 minutes at most, it’s believed that less than an ounce of it exists on Earth at any given time.
But perhaps the most menacing elements are those that silently radiate. These substances are known as radioactive elements, and they readily release energy, or decay, due to their highly unstable nuclear composition. This reactive nature is what’s harnessed to create some of the world’s most dangerous nuclear weapons. Radioactive elements typically emit energy in the form of alpha particles, beta particles, neutrons, or electromagnetic radiation. While all alpha particles are dangerous, which consist of two neutrons and two protons tightly bound together, they can be particularly hazardous. If heavy, positively charged alpha particles find their way into the body, they can easily bombard and kill any cell in their path. In fact, it’s theorized that a single gram of a single alpha emitter, polonium, could kill more than 50 million people.
Polonium was first discovered by Marie Curie, and unfortunately, her daughter, researcher Irène Joliot-Curie, may have been one of its first victims after an accident in the lab. Polonium is naturally rare with few commercial uses, so only a small amount is manufactured each year. Thallium, on the other hand, was not hard to find in early 1950s Australia. At the time, Sydney was suffering from a chronic rat infestation. Thallium was the main ingredient in a popular and inexpensive rat poison called Thall-Rat. Fortunately, detectives were able to connect the dots, and in 1953, the Australian Parliament effectively banned all sales of thallium.