New MRI Scanners Risk Mercury Amalgam Release

Slightly disturbing story in the Independent today.

Modern MRI machines pose mercury poisoning risk for people with fillings


I’m not sure if the new scanners are widely used yet in UK hospitals but they are getting more so in the US (take note our US readers!). I would be asking which scanner they are using if you have amalgams. Here is a quick summary and commentary for you…

Modern MRI machines could poison people who have dental fillings, because new high-powered scanners can cause mercury to leak out of previously set fillings, a study has found. 

Research published in the journal Radiology, found levels of the poisonous metal were much higher after they were exposed to the strong magnetic fields the new MRI scanners can generate.  The study’s lead author, Dr Selmi Yilmaz, a dentist at Akedniz University in Turkey, said strong magnetic fields have been shown to cause leakage. 

In the past few years NHS hospitals in England & Scotland have acquired MRIs capable of producing a seven Tesla (T) – the unit of magnetic force – field.  Most conventional MRIs produce a field of between 1.5 & 3-T.  To test these new machines’ effects Dr Yilmaz and colleagues created cavities in several teeth and filled them with mercury amalgam.   After the filling had hardened the teeth were placed in an artificial saliva solution, then 3 sets of 20 randomly selected teeth were either exposed to 20 minutes of 1.5-T MRi, 7-T MRI, or given no MRI exposure. 

The mercury content in the saliva containing the 7-T MRI teeth was nearly 4 times higher than the lower powered scan – 0.67 parts per million compared to 0.17ppm – far higher than is safe.  

“Although it is not clear how much of this released mercury form is absorbed by the body, the study findings indicate that amalgam fillings may pose a risk not only to patients, but to staff too,” Dr Yilmaz said. 

British Dental Association (BDA) said the mercury risk of amalgam fillings will become less significant from July, when an EU law aimed at protecting people from mercury in all forms comes into effect, but this won’t help those who already have fillings.  Scientific adviser to the BDA, Prof Damien Walmsley, told The Independent: “This will be a decreasing problem in time but the development of new ultra-high-strength scanners, which were only approved by US Food & Drug Administration last year, needs to be reviewed closely.”   He stressed the study showed “no cause for concern” from older conventional MRIs

Comment: It’s not correct that mercury fillings will be stopped in July – it’s only the first stage of a slow phase-out which UK tried to delay. According to BDA the EU regulation states that from 1 July 2018 dental amalgam should not be used to treat children under 15 years of age and in pregnant and breast feeding womenexcept when deemed strictly necessary by the dental practitioner based on the specific medical needs of the patient.  So this will be an issue for years to come.

And, if you do have amalgams or suspect high mercury, read the Mercury factsheet here. I’ve done a few now of the new Tri-Test and it is fascinating to see if people have high inorganic mercury (from amalgams) or methylmercury (from fish). Happily, so far, most people have been pleasantly surprised that their levels are not as high as they feared, although I did have one yesterday who was pushing it. I suppose it would be interesting to see some test results after having one of these new scans – you could always test to see if it is causing a problem if you had to have one.

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