Thallium Poisoning

Thallium is the chemical element, represented by the chemical symbol TI. Thallium can be found in trace amounts in earth's crust, and earlier it was obtained mainly as a byproduct from the smelting of metals like, lead, copper and zinc. Today thallium is mainly obtained from its reserves. This metallic element is usually soft gray in color and resembles tin, but when exposed to air it discolors and become bluish gray in color. Thallium, as well as its compounds are known for being highly toxic and they can be easily absorbed by the skin. Thallium poisoning can occur, if someone gets exposed to a large amount of thallium. Such poisoning can be caused due to inhalation or accidental ingestion of thallium and its compounds. Even skin contact can be dangerous, for which a lot of precautions need to be maintained while handling thallium.

Thallium Toxic Effects on the Body

Exposure to a high level of thallium can have several harmful effects on our body. The toxicity of thallium is mainly due to the resemblance of univalent thallium ions to potassium ions in aqueous solution. Due to this resemblance, thallium can enter the body by substituting itself for potassium. This however, disrupts many vital cellular processes taking place within the body, which can manifest in several symptoms. Long term exposure to thallium in large amounts can eventually affect the nervous system. Ingestion of high level of thallium even for a short time period can affect the heart, lungs, liver and the kidneys along with the nervous system. The effects of ingesting a small amount of thallium for a prolonged time period is however, not known with certainty.

Thallium Toxicity Symptoms

• Nausea and vomiting
• Diarrhea
• Severe abdominal pain
• Blood in stool
• Numbness of the extremities of the body like, fingers and the toes
• Temporary hair loss
• Loss of reflexes
• Headache
• Confusion
• Agitation
• Delirium
• Shortness of breath
• Muscle wasting
• Convulsions
• Dementia
• Psychosis
• Coma

Chronic poisoning on the other hand, can cause hair loss, headaches, loss of appetite, excessive tiredness, leg pain, vision disturbance and depression.

Thallium Toxicity Treatment

It can be treated with Prussian blue, which is the antidote for thallium. Prussian blue is administered orally to prevent the absorption of thallium in the intestine. It absorbs thallium, while releasing potassium inside the body. The thallium contaminated Prussian blue then comes out via the stools. This treatment option is effective, if administered within 6 hours, following the ingestion of thallium. Other treatment options available are dialysis and as few medications, that can help to treat this poisoning by increasing the excretion of thallium. Diuresis and potassium chloride are also used to increase the excretion of thallium. Sometimes, EDTA (ethylenediaminetetraacetic acid), penicillamine, sodium iodide, thiouracil and dimercaprol are also used for treatment.

Despite its toxicity, thallium was widely used in ant killers and rat poison. Today, it is used for producing low melting glasses, specialized eyeglasses, transmission devices, photoelectric sensors, imitation diamonds, infrared detection and electronic devices. A very small amount of thallium is also used in myocardial perfusion test, which is a diagnostic test for evaluating several heart conditions. It is very important to handle this substance carefully. In this regard, government has set certain guidelines related to the exposure of thallium in workplaces. The Occupational Safety and Health Administration (OSHA) has established the exposure limit of thallium at 0.1 mg per cubic meter in workplace air. On the other hand, the National Institute for Occupational Safety and Health (NIOSH) has suggested that presence of 15 mg per cubic meter of thallium be considered as dangerous for life.