Thallium Toxicity: Mechanisms of Action, Available Therapies, and Experimental Models

Thallium (Tl) is a non-essential and highly toxic heavy metal capable of replacing potassium (K+) in biological systems, leading to mitochondrial dysfunction, oxidative stress, and inhibition of protein synthesis. In humans, the estimated oral lethal dose ranges from 10 to 15 mg/kg, with acute mortality rates of 6–15% and chronic neurological sequelae in up to 55% of survivors. Environmental releases of thallium of up to 5000 metric tons annually from industrial and mining activities, combined with its high oral bioavailability and nonspecific multisystemic symptoms, underscore the urgent need for more effective therapeutic strategies. This review summarizes current evidence on Tl toxicity, including its mechanisms of action, clinical manifestations, and available treatments. It emphasizes the strategic selection of biological models: simple organisms such as Caenorhabditis elegans and Drosophila melanogaster enable high-throughput screening and early biomarker detection; zebrafish (Danio rerio) provide vertebrate-level evaluation of multi-organ effects; and rodent models offer systemic toxicokinetic and therapeutic validation. Human-derived organoids and induced pluripotent stem cell (iPSC) systems recreate tissue-specific microenvironments, allowing translational assessment of mitochondrial, neuronal, and cardiac toxicity. Integrating these models within a tiered and complementary framework, alongside environmental and clinical surveillance, can accelerate the development of targeted treatments and strengthen public health responses to Tl exposure.