# Thallium Use, Toxicity, and Detoxification Therapy: An Overview
## 3 Thallium Toxicity  
Although being a highly toxic element, thallium has been studied to a much lesser degree than other toxic elements such as lead, cadmium, or mercury [31; 32]. This happens mainly because Tl is often undetected by classical analytical methods which tend to have poorer sensitivity for Tl than for other elements. All forms of thallium are soluble enough to be toxic to living organisms [1]. Tl is a colorless, water-soluble, tasteless, and affordable element; therefore, it may cause isolated and massive human poisoning. The first symptoms (Table 2) of poisoning can be different and non-specific, making differential diagnosis difficult. The effects of Tl toxicity in human beings arise after a couple of weeks from its \begin{table}
\begin{tabular}{l c} \hline Atomic number & 81 \\ Atomic weight & 204.38 u \\ Thallium isotopes (41) & from 176 u to 216 u \\ Electronic configuration & [Xe] 44\({}^{11}\)5d\({}^{10}\)6s\({}^{2}\)6p\({}^{1}\) \\ Melting point & 304 \({}^{\circ}\)C \\ Boiling point & 1473 \({}^{\circ}\)C \\ Density at 20 \({}^{\circ}\)C & 11.85 g/cm\({}^{3}\) \\ Atomic radius & 170 pm \\ Van der Waals radius & 220 pm \\ Heat of fusion & 4.14 KJ/mol \\ Heat of vaporization & 165 KJ/mol \\ Pauling electronegativity number & 1.62 \\ First ionization energy & 589.4 KJ/mol \\ Second ionization energy & 1971.4 KJ/mol \\ Third ionization energy & 2878 KJ/mol \\ Electrical resistivity at 20 \({}^{\circ}\)C & 0.18 m \\ \hline \end{tabular}
\end{table} 
Table 1: Physical and chemical properties of thallium (Tl). administration, with alopecia being the main symptom, firstly with hair loss, then complete baldness, followed by axillary and public hair loss. Thallium poisoning becomes troubling when other symptoms occur such as gastrointestinal problems (nausea, vomiting and diarrhea), peripheral and central nervous system disorders (dysesthesia, ataxia, tremors, convulsions, paralysis, sleeplessness, hallucinations, and delirium), and cardiac problems, such as tachycardia and hypotension, lethargy, and coma) [33; 34]. Thallium poisoning can even lead to death. Thallous sulfate is odorless and tasteless and was once successfully used as a household rodenticide and insecticide, but many countries in the Western word have banned such use due to numerous cases of unintentional or criminal poisonings of humans. After numerous cases of unintentional poisonings, the commercial use of thallium salts as household poison for rats, squirrels and ants was banned in the West [35]. Tl has been described as an infamous adulterant added to opioids, heroin, and cocaine [36; 37]. In mammals, Tl is more toxic than mercury, lead, zinc, \begin{table}
\begin{tabular}{c c} \hline \hline  & **References** \\ \hline
**Cardiac symptoms** & [33; 34] \\ \hline Coma & \\ Hypotension & \\ Lethargy & \\ Tachycardia & \\ \hline
**Dermatological symptoms** & [34] \\ \hline Alopecia (after about 3 weeks) & \\ Anhidrosis & \\ Hypohidrosis & \\ Mees lines on the nails (after about 1 month) & \\ \hline
**Gastrointestinal symptoms** & [34] \\ \hline Diarrhea or constipation & \\ Nausea and vomiting & \\ Stool containing blood & \\ \hline
**Hematologic symptoms** & [34] \\ \hline Anemia & \\ Eosinophilia & \\ Leukocytosis & \\ Neurothilia & \\ Thromboyopenia & \\ \hline
**Neurologic symptoms (after 3-5 days)** & [33; 34] \\ \hline Ataxia & \\ Convulsion & \\ Death & \\ Distal muscle weakness of the hands or feet & \\ Hallucination & \\ Headache & \\ Insonnia & \\ Paresthesia & \\ Tremor & \\ \hline
**Ocular symptoms** & [34] \\ \hline Atrophy of the optic nerve & \\ Cranial nerve 7 th palsy & \\ Nystgamus & \\ Lens opacity & \\ Optic neuropathy & \\ Ptosis & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Symptoms of thallium exposure. cadmium, and copper. Thallium is absorbed by the ingestion of polluted food of animal and vegetable origin, and the inhalation of contaminated air, through skin contact and mucous membranes; it is distributed throughout the body by the blood and can cross the encephalic and placental barriers.