Thallium Poisoning - A Review

Abstract

Thallium is one of the most toxic of the heavy metals. Its continued use as a rodenticide in many developing countries and its increasing use in an expanding number of new technologies raise concerns about exposure risk to animals and humans. Thallium is a tasteless, odorless, and water-soluble chemical element for which both accidental intoxication and criminal poisoning have been reported. Thallium poisoning is one of the serious toxicities known to man. The symptomatology of its toxicity is usually nonspecific due to the multi-organ involvement.1 The initial symptoms of thallium poisoning may include fever, gastrointestinal problems, delirium, convulsions and coma. Common symptoms are mild gastrointestinal disturbances, polyneuritis, encephalopathy, tachycardia, skin eruptions, stomatitis, atrophic changes of the skin, nail changes (Mee's lines), and skin hyperesthesia (mainly in the soles of the feet and the tibia).1 The current therapy for thallium poisoning is the use of prussian blue and potassium chloride. Potassium therapy is probably the single most effective agent in the treatment of thallium poisoning. Treatment with prussian blue (or activated charcoal) will interrupt the enterohepatic cycling of Thallium, thus enhancing fecal elimination of the metal. Forced diuresis with potassium loading will increase the renal clearance but should be used cautiously because neurologic and cardiovascular symptom may be exacerbated.2 If recognized and treated early, Thallium poisoning carries a favorable prognosis for full recovery.