Toxicity Summary for Thallium:
Main risks and target organs
Target organs are the peripheral and central nervous
system, the gastrointestinal tract and the skin, especially
the hair follicles. In severe poisoning, the patient may die
early of myocardial failure.
Summary of clinical effects
In acute thallium poisoning the onset of symptoms is
often insidious reaching a maximum in the second or third
week after exposure. The initial clinical features include a
gradual development of gastrointestinal disturbance (severe
constipation), hyperaesthesia, paraesthesia, hyperalgesia of
the lower limbs (affecting especially the soles of the foot),
followed by motor weakness of the lower limbs and foot drop.
Encephalopathy and retrobulbar neuritis occur in severe
poisoning. At the end of the second week, the characteristic
symptom of hair loss appears. Development of psychiatric
disturbances ranging from hysterical behaviour to complete
psychosis may be observed. In severe poisoning the patient
may die early of myocardial failure.