Thallium (tā), with the symbol [TI], is a tasteless and odorless silvery white metal and one of the rare elements widely distributed on the earth. Thallium salts usually exist in soil in the form of monovalent or trivalent silicate minerals and sulfides. Thallium salt is a colorless and odorless crystal, which has no special taste after being dissolved in water.

At normal temperature and pressure, thallium is a tasteless and soft blue-white metal with an unprotected oxide film on its surface. Thallium metal has a melting point of 304℃, a boiling point of 1457℃ and a density of 1 1.8 g/cm at 20℃. Thallium is soluble in water, rapidly soluble in nitric acid and slowly soluble in acids, such as dilute hydrochloric acid and dilute sulfuric acid.

Thallium is a typical rare dispersed metal. Although it is rarely found in nature, it is widely found in minerals, soil, seawater and biomass. Thallium can be enriched by solvent extraction, ion exchange, chromium salt precipitation-zinc replacement and other methods. Thallium and its compounds can be used in medicine, electronics, optics and other fields.

What are the early symptoms of thallium poisoning?

Thallium is a toxic heavy metal, which has strong neurotoxicity and can also damage the liver and kidneys. In the case of acute thallium poisoning, there is usually a certain incubation period, and the length of incubation period is related to the exposure. There are digestive tract symptoms in the early stage, such as anorexia, nausea, vomiting, abdominal pain and diarrhea, and obvious nervous system disorder appears a few days later.

If it is chronic thallium poisoning, the onset is slow, and early symptoms can be neurosis, such as headache, drowsiness, insomnia, memory loss, and difficulty in recognition.