Thallium, Tl, is a chemical element of Group III of the periodic table of elements of DI Mendeleev . Sequence number 81, atomic weight 204.37. Silver-white metal, melting point 303.5 °, density 11.85. In compounds it is mono- and trivalent. Thallium and its compounds are used for the manufacture of glass, luminous paints, photocells, poison for rodents (celiopastes), preparations for removing hair, etc.
Thallium compounds are strong poisons that affect the central nervous system, the gastrointestinal tract, the kidneys , and also cause hair loss (a pilotropic effect).
First aid for poisoning - washing the stomach with water with activated carbon and 0.3% sodium thiosulfate solution. When working with thallium and its compounds, the use of respirators and protective clothing is mandatory; periodic medical examinations with the participation of an ophthalmologist dermatologist, neurologist.
The maximum permissible concentration of thallium (iodides, bromides) is 0.01 mg / m 3 .