Dental Services in Bray, Co Dublin

Holistic Dentistry Blog


How Did Thallium Get Into Patients’ Fillings?



Regular readers and patients will know that as a former GP and current holistic dentist, I’m committed to caring for the health of the whole person and not just the oral cavity when providing treatment. For this reason, I am wholly against the use of mercury in any dental treatment that is why I haven’t placed an amalgam filling in over 20 years.

When you’ve spent decades treating patients for mercury poisoning as a result of amalgam fillings, you begin to think nothing could shock you anymore. That was until I discovered that patients were not only having mercury placed in their mouths, but all kinds of dangerous metals, including thallium.

Susan Ryan had been very ill for 7 long years. When she came to see me, her symptoms and dental make up suggested that her silver fillings could be the cause of her ill-health. Once I had safely removed her silver fillings in my surgery, I had them tested by a biochemist.  I was shocked to read the results. They reported levels of thallium of up to 2423 mg/Kg. This means that thallium made up 2.423% of the weight of the filling. Given how poisonous thallium is, (as you’ll understand as you read on) to find this much amalgam in a tooth filling is quite shocking. And Susan was definitely suffering the effects.


What Is Thallium?

William Crookes discovered thallium in 1861. If you remember your chemistry, you’ll recall thallium’s chemical symbol is TI on the periodic table. It occurs naturally in the earth’s crust but at very low concentrations.

thallium in amalgam fillings

It was initially used in medications for illnesses including night sweats and ringworm as well as sexually transmitted diseases such as syphilis and gonorrhoea (Cvjetko et al, 2010). The effectiveness of thallium in treating these illnesses was never clear, but its use didn’t become widespread once the side effects of thallium became apparent.

Thallium was also used in rat poison in the 1900s. The use of poisons containing thallium has been banned in most countries following a World Health Organisation recommendation on the issue in 1973.


Why Thallium Is So Dangerous To Humans

Considering it is banned in rat poisons, it’s unsurprising that thallium is highly toxic to humans. Its effects are usually exerted slowly in the human body, with early wide ranging symptoms including gastrointestinal problems such as nausea and vomiting. One might experience constipation and symptoms such as pain in the hands or feet due to nerve damage, feeling excessively thirsty and insomnia.

In the human body, thallium is so toxic because of its similarity to potassium and sodium ions. does a great job of explaining why this impacts negatively on the human body;

Potassium ions have a number of roles in the body, including the transmission of messages through nerves; however, the body cannot distinguish between thallium and potassium, and the incorporation of thallium ions instead means that these roles cannot be carried out.

Once absorbed, thallium passes from the blood, into the body’s tissues, poisoning the kidneys, bones, stomach, intestines, spleen, liver, muscle, lungs and brain. Studies have shown that thallium can cross the placental barrier, putting pregnant women and their babies at risk and it can pass the blood-brain barrier, causing neurodegeneration. (Cvjetka et al, 2010).


Thallium: The Poisoner’s Poison

thallium is highly poisonous

Due to its slow but highly toxic effects, thallium has been called “The Poisoner’s Poison”. There have been high profile murder cases in the recent past where thallium has been used as the murder weapon. Tianle "Heidi" Li, was convicted in 2013 of murdering her husband, Xiaoye Wang by feeding him the odourless, tasteless and slow acting thallium. Due to its toxicity, thallium is not easy to source. It was only because Li worked as a research chemist that she had access to the poison.

Naturally, finding thallium in the silver fillings of my patients was a real shock. I have to agree with Dr Hulda Regehr Clark when she says;

“Thallium pollution frightens me more than lead, cadmium and mercury combined, because it is completely unsuspected.”


Who Puts Thallium In Fillings?

It is hard to fathom why an extra poison would be added into the mix of an already highly toxic substance like amalgam. Thallium makes its way into amalgam well before it reaches the dental surgery. It is thought it is most likely as a result of recycled mercury thermometers. As mercury freezes at -39C, thallium is used in mercury thermometers in arctic conditions as an anti-freeze. When these thermometers are recycled, the mercury and the thallium end up in the amalgam, which is then placed in a patient’s mouth.

This irresponsible recycling of mercury shows a dangerous disregard for patients’ welfare.


Susan’s Story of Thallium Poisoning

Of all of the patients whose fillings I have found thallium in, Susan’s returned the highest reading I have ever seen. 2423 mg/Kg (or 2.423% of her filling was thallium).

Susan was constantly and mysteriously ill for 7 years. She suffered with vomiting every morning. It’s hard to imagine how debilitating this must have been. Susan underwent endless tests and visited various specialists only to be incorrectly told that her symptoms were likely a due to psychological problems.

In 2010, Susan first visited my practice. It soon became clear to me that her large mercury-containing amalgam fillings were the most likely cause of her illness. Of course, it was only when these fillings were tested after their removal that we became aware that as well as mercury, thallium was also present. Just three weeks after extensive dental work to remove her fillings, Susan’s nausea and vomiting disappeared completely.

She still attends our dental practice today and at her last check-up she reported that her health was very good.

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