– Polonium is a rare and highly radioactive metal
– “Po” on the periodic table (atomic no.84)
– Tiny traces of polonium-210 (210Po) the only naturally occurring form due to its short half-life
– The first element to be discovered because of its strong radioactivity
– A lethal dose is 15 megabecquerels (0.41 mCi), or 0.089 micrograms (μg)
– Administered to humans for experimental purposes in the mid ’40s
– Irene Joliot-Curie thought to be first person to die from exposure to polonium
– Used to murder Russian agent defector Alexander Litvinenko
– Its presence in tobacco contributes to lung cancer deaths
Discovered by Marie and Pierre Curie in 1898, polonium is a rare and highly radioactive metal of which only polonium-210 is the only naturally occurring form thanks to its short half-life of 138 days (found in uranium ores). Polonium emits alpha particles which are dangerous to organic tissue if absorbed, inhaled or ingested. They can’t penetrate the epidermis so as long as alpha particles remain outside the body they aren’t a threat to health.
The tiniest exposure is lethal at only 15 megabecquerels (0.41 mCi), or 0.089 micrograms (μg). To put this into context, a grain of table salt is about 60μg making polonium 250,000 more toxic than cyanide, and it has been estimated a single gram of vaporized polonium could kill over a million people (although a nuclear reactor would be needed for this).
The poison doesn’t kill immediately with death taking days or weeks to occur. Symptoms include headaches, diarrhea and hair loss while a slow but complete breakdown and failure of the internal organs occurs.
Irene Joliot-Curie (the daughter of Marie and Pierre Curie) is thought to have been the first to die from exposure to 210Po. A sealed capsule of the element was on her lab bench when it exploded in 1946. Ten years later she died from leukemia.
It’s been theorised that several deaths in Israel in the 1960’s were from 210Po after a leak was discovered in a laboratory in 1957. Traces of 210Po were found on the hands of a physicist who researched radioactive material. Medical examinations found no issues, but they didn’t test his bone marrow and he died from cancer. As did one of his students and two colleagues. There’s never been a formal admission of any connection between the leak and deaths.
It was thought 210Po was used to murder Yassir Arafat as his clothing and skin had traces of 210Po, although an investigation ruled otherwise.
The most famous case of 210Po poisoning was the 2006 murder of Russian spy and defector, Alexander Litvinenko. He drank a cup of green tea laced with 210Po at levels 200 times greater than a fatal dose. Litinenko’s public deathbed accusation was that Russian president Vladimir Putin was behind his murder. It took him three weeks to die.