The Invisible Poison: How Polonium-210 Became a Modern Weapon

Health · Published 30 September 2026 Swipe more like this →

In short: Most radiation detectors are useless against polonium-210. This radioactive isotope emits very little gamma radiation but releases massive amounts of alpha particles, acting like a short-range weapon on living cells once ingested or inhaled. In 2006, it was used to execute a high-profile defector in London.

On November 1, 2006, Alexander Litvinenko, a former KGB officer turned UK defector, fell ill after meeting with two Russian ex-intelligence officers at a London hotel. He quickly developed severe symptoms, including vomiting and bloody diarrhea, eventually leading to his hospitalization. While doctors initially treated him for gastroenteritis, the severity of his condition—characterized by extreme physical weakness and periods of unconsciousness—suggested a much more sinister cause than a common stomach ailment.

The investigation into his death revealed a sophisticated use of polonium-210, a radionuclide that was once a critical component of early nuclear bombs. Because it primarily emits alpha particles, standard Geiger counters used by hospital staff and police initially failed to detect the poison. It wasn't until a scientist overheard a discussion about a tiny 'gamma ray spike' in Litvinenko's blood samples—barely visible above background noise—that the specific isotope was identified. This discovery marked the first time polonium-210 had been documented as a weapon used against a human.

The mechanism of the poisoning was devastating: once ingested, the polonium acted on his internal organs like an internal furnace. Estimates suggest Litvinenko received approximately 1.85 GBq (about 10 micrograms) of the substance, which was roughly 200 times the median lethal dose for ingestion. In September 2021, the European Court of Human Rights ruled that Russia was responsible for the assassination, ordering damages and costs in a case that highlighted the terrifying potential of using rare, hard-to-detect radioactive isotopes as tools of state violence.

The case also underscored the difficulty of forensic toxicology. Early tests suggested thallium poisoning due to Litvinenko's hair loss, but physicians later noted his chemical levels were inconsistent with toxicity. It was eventually determined that he had been poisoned via a teapot at the Pine Bar, where he drank green tea. The use of such a specific, difficult-to-detect radioactive isotope created significant diplomatic friction and remains a landmark case in modern clandestine warfare.

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