Thallium (204,38 a.m.u.) not a vital element. Total amount in body is approx. 0,1 mg, but the amount of intake with food is not significant. After absorption in blood, thallium ions are quickly spreading in tissues, but part is deposing in erythrocytes. In blood thallium is mostly present in form of free ions Tl+.
In increased concentrations, thallium is toxic. It is caused by disorder of metabolism of essential organism cations – sodium and potassium. Rat poison, some fungicides and pesticides are thallium compounds. Thallium salts (sulphate, acetate) are used in some medicines, cosmetics, but radioactive thallium – in radiology diagnostic procedures.
Increased concentrations of thallium could be discovered near metallurgical production, coal plants, in glass manufacturing on chemical factories. Soluble thallium compounds are easily absorbed in gastro-intestinal tract, easily absorbed through skin and respiratory passages. Period of thallium presence in human body is small: half-period is lesser than two days, but after 25 days after intoxication just a small amount of intaken dose is still present. Main way of excretion – kidneys, second one – intestinal tract. Lethal dose of thallium for human is approx. 10 – 15 mg/kg.
Intoxication symptoms increasing soon after the intake of high doses of thallium include sickness, vomit, stomach pain, diarrhoea, gastro-intestinal bleeding, pulmonary oedema. Later signs of nerve system disorders are being indicated – brain fog, motion coordination disorders, choreatic movements, spasms and sight disorders. Peculiar sign of chronic intoxication with thallium (thallium toxicosis) is alopecia (diffusive hair loss). If doses are 8 mcg/kg; in 2 – 3 weeks a hair is lost and paralyses appears.