Polonium was discovered by Madame Curie from uranium residue in 1898. It is a very rare but highly radioactive element with many isotopes, such as polonium -209, polonium -208 and polonium -2 10. Its industrial use is to eliminate static electricity generated by winding paper, cables and metal sheets, and to remove dust from photo negatives. In addition, the specific activity of polonium -2 10 is high, and the generated alpha ray can react with hydrogen to generate neutrons, which can be made into a neutron source with small volume and high neutron intensity and used to manufacture the trigger device of a nuclear bomb.

Polonium -2 10 is a highly toxic nuclide. Compared with cyanide with the same weight, the toxicity of polonium is about 250 million times (0. 1 g sodium cyanide can cause death). Because polonium and its alpha rays can't penetrate the skin on the body surface, polonium will cause radioactive damage to internal organs only after it enters the body to produce internal radiation, and large doses of radiation will lead to serious radiation sickness and even death. Litvinenko suffered from heart failure, hair loss, severe damage to the immune system and nervous system, and eventually died after receiving extremely high doses of radiation.

Excrements containing polonium -2 10 can pollute and spread the biological chain again in vitro.