What is Thallium Toxicity?
Thallium is a chemical element represented by the symbol TI on the periodic table. This substance was previously used as an ant and rat killer known as thallium sulfate. If a person is exposed to thallium at the workplace, the accepted limit is 0.1 milligrams per cubic meter (mg/m3) in an eight-hour workday. Anything above 15 mg/m3 is immediately harmful to one’s health. One notable property of thallium is that it can be easily absorbed through the skin and through inhalation. Since thallium has no taste or smell and can dissolve in water, there have been cases of accidental and intentional thallium poisoning.
Thallium salts were historically used to cure skin fungal infections. In the field of nuclear medicine, before the use of technetium-99m, a radioactive isotope thallium-201 was commonly used and is still applied for stress tests to screen for coronary artery disease, which is a condition associated with the heart. This form of thallium is over 4,000 times less potent. The application of thallium in this case allows physicians to assess the blood supply to the tissues in the body. The use of exercise or drugs to widen normal coronary arteries can alter the circulating blood and cause a reduction in blood flow through the coronary arteries, known as coronary steal syndrome.
Naturally, Thallium is a gray metal that is not found freely in nature. Even while it resembles tin when isolated, thallium changes color when it comes into contact with air.
Thallium can enter the body in various ways including absorption through the skin, inhalation and through the digestive system.
What Causes Thallium Toxicity?
Back in 1965, the United States banned the use of thallium in households and then commercially in 1975. Thallium poisoning can often look similar to other diseases, which means it might be overlooked in sick people. Nowadays, thallium is primarily used in the production of semiconductors and optics. However, it’s also found in rat poison and ant killer; and since it doesn’t have a taste or smell, it has sometimes led to accidental poisonings or has even been used criminally. While it’s no longer common in the U.S., thallium is still used in rat and insect poisons in other countries. In African countries, it’s been used as a pesticide, causing food contamination. There have even been instances where Chinese herbal medications have been contaminated with it.
People can get thallium poisoning if they consume it over time through their skin, their lungs, or their digestive system. There have been reports of people snorting it unknowingly when using cocaine, accidentally injecting it when using heroin, or even absorbing it through their skin even while wearing protective gloves.
There are several ways one could be exposed to thallium, such as:
– Through work-related exposure
– Accidentally swallowing it
– Using contaminated drugs
– Eating contaminated fish or other foods
– Being around hazardous waste sites
– Poisoning by a perpetrator
Risk Factors and Frequency for Thallium Toxicity
In the United States in 2019, the American Association of Poison Control Center reported 49 cases of thallium poisoning with one severe case and no deaths. Thallium toxicity is prevalent in developing countries, but we don’t have a lot of data on it.
- Thallium poisoning can be fatal in 6% to 15% of acute cases.
- A lethal dose for humans is 10 to 15 mg/kg, but death can occur even at lower doses.
- Unfortunately, we don’t have specific data on age, sex, or race.
Signs and Symptoms of Thallium Toxicity
If you are exposed to thallium, you might experience certain symptoms. These symptoms can vary depending on the duration and intensity of the exposure. Acute exposure or short-term, intense contact with thallium often leads to symptoms that affect your stomach, nerves, and skin.
- Stomach problems include abdominal pain, nausea, vomiting, and sometimes blood in your vomit or poop.
- Neurological issues are difficulties with movement, balance, sleep, and sometimes seizures. This can get severe enough to cause a coma or death.
- Skin symptoms often start with rashes or acne-like outbreaks, and after a few weeks hair loss can occur due to disruption in hair structure. Specific lines, known as Mees lines, may also appear on the nails about a month after poisoning.
Long-term or chronic exposure to thallium can carry out the same symptoms, but even as the thallium levels in your blood decrease, the neurological symptoms would persist.
There are also specific symptoms that relate to the eyes, including double vision, drooping of the upper eyelid, involuntary eye movements and blurred vision. Other general symptoms that may occur include fast heart rate or high blood pressure.
During a physical examination, the doctor will likely examine the abdomen (You may need to have a stool guaiac test, which checks for blood in the stool), neurological status (Testing your senses, balance, and strength in your lower body may be needed) and vision (An examination of the inside and the surface of the eyes are required).
Testing for Thallium Toxicity
If your doctor is trying to diagnose a thallium exposure, they will conduct specific tests. The most definitive diagnosis is made by detecting elevated thallium levels in your hair, nails, blood, urine, feces, and saliva. A 24-hour urine thallium concentration is the preferred method; it measures the amount of thallium in your urine over a whole day and provides the most accurate results. This test is done using a testing process called atomic absorption photospectrometry. While there’s also a quicker urine spot test, it can often give false-positive results. Similarly, testing the blood thallium levels might show a falsely negative result meaning the test says you don’t have the condition even though you actually do.
Your doctor may order further tests like a complete blood count (to evaluate your overall health), electrolyte balance (to check if the levels of key minerals in your body are within the normal range), glucose (to measure your blood sugar level), blood urea nitrogen (a test that measures how well your kidneys are working), liver function test (to ensure that your liver is functioning properly), and calcium (to ensure your calcium level is normal).
Thallium, if ingested, can be seen on radiographic images (similar to X-rays) because it is radiopaque, meaning it blocks or absorbs radiation.
If you’re showing heart-related symptoms such as a racing heart, your doctor might conduct an electrocardiogram to assess your heart’s rhythm. If you’re experiencing seizures or showing some symptoms related to your nervous system, they may order an electroencephalogram (a test that measures your brain’s electrical activity) or a nerve conduction study (a test that measures how well and how fast the nerves can send electrical signals).
Treatment Options for Thallium Toxicity
Getting immediate care is crucial if you’ve been exposed to a harmful substance. The first step is to ensure that you are stable and that you can breathe properly. Your healthcare provider may also check your blood circulation. In many cases, removing clothes that may have been contaminated with the substance can help prevent further exposure. If you’ve swallowed the harmful substance, activated charcoal might be given, as it is particularly effective if administered within one hour of ingestion.
If you’ve been in contact with a harmful substance and visit the emergency department, there are certain steps that are typically taken. In case the substance has come into contact with your skin, it will be cleaned with soap and water to remove the substance. If your eyes were exposed, they will be thoroughly rinsed with room temperature water.
In the event that you’ve consumed a harmful substance, treatments like activated charcoal and Prussian blue may be used. These substances can help your body get rid of the toxins. Prussian blue, in particular, has been approved by the United States Food and Drug Administration for its efficacy in such situations.
What else can Thallium Toxicity be?
People suffering from thallium poisoning often show symptoms similar to a number of different conditions. These conditions should be considered when attempting to diagnose thallium poisoning:
- Carbon monoxide poisoning
- Arsenic poisoning
- Isoniazid poisoning
- Mercury poisoning
- Organophosphates poisoning
- Thiamine deficiency
- Diabetic polyneuritis
- Botulism
- Vasculitis
- Poliomyelitis
What to expect with Thallium Toxicity
The earlier treatment starts, the better the chance of recovery. However, if the exposure has been ongoing, the recovery process can take a long time. If detoxification therapy gets delayed, there could be lasting damage to the nervous system.
Patients might continue to show signs and symptoms of peripheral neuropathy – a condition that results in weakness, numbness, and pain particularly in the hands and feet – up to six years after the initial exposure. Reports indicate that lasting effects are most common in the feet and lower parts of the body.
Possible Complications When Diagnosed with Thallium Toxicity
Neurological harm can sometimes be long-lasting. This usually affects the feet and lower parts of the body. Certain mental health symptoms have also been observed. These include:
- Restlessness
- Aggressive behaviors
- Feelings of intense sadness
- Changes in personality
Preventing Thallium Toxicity
If someone accidentally comes into contact with thallium, it’s crucial to wash the affected skin with tap water immediately and get rid of any clothes that might be contaminated. Thallium is a toxic substance that can cause serious health problems if it gets into your body. If someone has intentionally swallowed thallium, they should speak to a mental health professional for evaluation and support.
Paying special attention to keeping the mouth clean is also important. This is because thallium can cause damage to the gums, teeth, and other areas of the mouth.
Hair loss can be a side effect of thallium exposure, and for this, some patients might find shaving their head beneficial. This can help reduce the emotional stress caused by falling hair and can help to improve their overall wellbeing.
Patients who have been exposed to thallium should be closely monitored by healthcare professionals. Regular follow-ups help ensure any side effects or problems caused by the exposure are treated as soon as possible.
