Neurotoxicity of thallium: Old issues and new developments

Abstract Thallium (Tl+) is a toxic heavy metal that, due to its peculiar characteristics such as being odorless, tasteless and colorless, may be responsible for several intoxications by accidental, occupational or intentional exposures. Medical cases report the severity of the signs and symptoms that, is many cases can, culminate in death. Basic research has made considerable efforts to explain the mechanisms of Tl+ toxicity in several models (in vivo and in vitro), administration schemes and times of exposure. Findings are consistent with functional mitochondrial alterations, oxidative stress and imbalance in antioxidant defenses and alterations in glutamatergic and other neurotransmission systems, all of them actively participating in the toxic pattern elicited by the metal. This chapter offers an updated general vision, based on past and recent scientific evidence, pointing to relevant issues about Tl+ contamination in the environment, exposure and risks to human health, and toxic mechanisms.