Since its discovery in 1861,1 thallium has been widely used for the treatment of ringworm of the scalp, dysentery, syphilis, gonorrhea, gout, and night sweats of tuberculosis.2 Its toxicity, however, has led to its abandonment in therapy.
Munch reported an outbreak of thallotoxicosis in 19333 in Mexican workers who accidentally ingested food made with "Thalgrain," a pesticide containing 1% thallium sulfate. The same author reviewed the literature and found 778 additional cases of human poisoning of which 6% were fatal.4 Thallium salts have been used as pesticides since their introduction in Germany in 1920.5 Most of the reported cases of thallium poisoning have been caused by accidental or suicidal ingestion of rodenticides.6-11
The clinical picture is extremely variable and the diagnosis particularly difficult in children. Gastrointestinal symptoms are common: hemorrhagic gastroenteritis, stomatitis, glossitis, abdominal pain, vomiting, diarrhea, and a bluish line in the gums. All appear 12-14 hours after the