Gallium, Indium, and Thallium

Abstract

The chemical elements gallium, indium, and thallium belong to group IIIA in the periodic table. Unlike other metals, such as lead and arsenic, which have been featured prominently in toxicologic folklore since antiquity, they are relative newcomers, discovered from 1861 to 1876. Since then, thallium has developed a well-deserved reputation for its toxic properties and is recognized as a potent accidental, occupational, and environmental poison, with incidence in cases of homicide and suicide. Although gallium and indium are not as toxic as thallium, their production and industrial use represent an important source of exposure, particularly in the increasing manufacture of semiconductor electronic devices. Gallium compounds particularly produce pulmonary toxicity. Indium compounds induce pulmonary toxicity and also nephrotoxicity, hepatotoxicity, and developmental toxicity, whereas thallium compounds act as general poisons. Some compounds are also capable of altering various cellular defense mechanisms involved in carcinogenesis. However, many aspects of the toxicity of individual compounds in human beings, including toxicokinetics, mechanisms of action, teratogenic potential, and the best treatment, remain to be elucidated. Keywords: Gallium; Indium; Thallium; Gallium compounds; Indium compounds; Thallium compounds; Physical and Chemical properties; Production; Use; Exposure assessment; Toxic effects; Radiopharmaceuticals; Cancers; Cancer treatment; Toxic effects; Hodgkin's disease; Non-Hodgkin's lymphoma; Standards; Guidelines; Regulations; Environmental impact; Aquatic ecosystems; Alopecia