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What's the argument about? Haven't dental amalgams been used for 150 years? Can we really have been wrong about their safety for so long?


Let's begin by letting the FDA have their say. As the FDA defines it:

"Dental amalgam is a mixture of metals, consisting of liquid mercury and a powdered alloy composed of silver, tin, and copper. Approximately 50% of dental amalgam is elemental mercury by weight." [1]

The history of the ADA

Here's what the FDA says about the history of the amalgam:

"First introduced in France in the early 1800s…Amalgam has been the restorative method of choice for many years due to its low cost, ease of application, strength, durability, and bacteriostatic effects. Factors that have led to recent decline in use are a lingering concern about detrimental health effects, aesthetics, and environmental pollution." [1]

What the FDA's history leaves out, is the dramatic role of the dental amalgam in the founding of the American Dental Association (ADA). The truth is that before the ADA, there was the American Society of Dental Surgeons (ASDS). In the 1840s, contrary to what the ADA and FDA would have you believe about the very "recent" debate about mercury and the amalgam, a large number of dentists opposed the use of the amalgam due to concerns about mercury poisoning. As a result, in 1845 the ASDS and other affiliated dental societies required their members to promise not to use the amalgam. Some members were even suspended for malpractice when it was discovered they were using it. But,

"the advocates of amalgam eventually prevailed and membership in the American Society of Dental Surgeons declined, forcing it to disband in 1856. In its place arose the American Dental Association, founded in 1859, based on the advocacy of amalgam as a safe and desirable tooth filling material." [2]

There were good economic reasons for promoting the amalgam and ignoring the risks of mercury poisoning:

"Amalgam's introduction meant that dental care would now be within the financial means of a much wider sector of the population, and because amalgam was simple and easy to use, dentists could readily be trained to treat the anticipated large number of new patients." [2]

Of course, the ADA fails to mentions any of this in their history. It's not flattering after all: the ADA was in fact was founded in order to promote a lucrative--though dangerous--new technology that now, 150 years later, is increasingly defamed by experts around the world amidst a growing recognition of its hazard to human health.

Why is mercury used in the first place? Mercury allows the mixture and installation of a metallic alloy at a temperature low enough to be tolerable to the human mouth. Is the resulting compound completely stable and inert? Go to our chemistry page, where we discuss why it is not.

TOXICITY of the amalgam

Now, the FDA acknowledges that elemental mercury is a highly dangerous neurotoxin. Nor do they deny that amalgams leach mercury for as long as they are in the mouth. What the authorities deny, is that the amount of mercury released into to the body by an amalgam (or many amalgams) is dangerous. The whole argument rests on what a "safe" level of exposure is, and perhaps most importantly, how this is measured. The FDA defines dangerous levels of exposure as greater than 50-100 ug/g creatinine, which is a measurement obtained from urine. All informed scientists do not agree that:

  • 50-100 ug/g Cr is the level beyond which elemental mercury is dangerous.
  • Measurements obtained from the urine are reflective of mercury content in the body.

But before we present the counter-arguments, let's hear what the FDA has to say about mercury toxicity:

"Elemental mercury and inorganic mercury have been demonstrated for decades to be well-known toxicants in both laboratory animal and human epidemiological studies. In studies of workers in various occupations, mercury vapor, depending on the degree of exposure, can cause neurobehavioral changes, cognitive changes and kidney injury. Many of the preclinical and clinical effects associated with neurologic and renal endpoints have been reported at air mercury concentrations > 50-100 ug/m3 (associated urine mercury concentrations 50-100 ug/g Cr)." [3]


Despite the admission that elemental mercury is highly dangerous (some advocates of the amalgam will tell you that only methylmercury is dangerous), the FDA insists that the levels of exposure due to dental amalgams are safe:

"Dental amalgam...releases low levels of mercury vapor that can be inhaled. High levels of mercury vapor exposure are associated with adverse effects in the brain and the kidneys. FDA has reviewed the best available scientific evidence... Based on this evidence, FDA considers dental amalgam fillings safe for adults and children ages 6 and above.

The amount of mercury measured in the bodies of people with dental amalgam fillings is well below levels associated with adverse health effects. Even in adults and children ages 6 and above who have fifteen or more amalgam surfaces, mercury exposure due to dental amalgam fillings has been found to be far below the lowest levels associated with harm."[1]


The FDA goes on to state that amalgams present no danger to pregnant and nursing women. However, look carefully at the language they use:

"There is limited clinical information about the potential effects of dental amalgam fillings on pregnant women and their developing fetuses, and on children under the age of 6, including breastfed infants. However, the estimated amount of mercury in breast milk attributable to dental amalgam is low and falls well below general levels for oral intake that the Environmental Protection Agency (EPA) considers safe. FDA concludes that the existing data support a finding that infants are not at risk for adverse health effects from the breast milk of women exposed to mercury vapor from dental amalgam. The estimated daily dose of mercury vapor in children under age 6 with dental amalgams is also expected to be at or below levels that the EPA and the Centers for Disease Control and Prevention (CDC) consider safe."[1] (Emphasis ours)

Given that the risk to infants and fetuses is based on estimations, how did they arrive at these calculations? The truth is that an "uncertainty factor" is employed to estimate the risk to fetuses. In other words, they don't know:

The Agency for Toxic Substances and Disease Registry (ATSDR) "considers that the MRL for elemental mercury, while derived from exposures in an adult worker cohort, uses a standard uncertainty factor approach to ensure that it is protective for adverse effects in any sensitive subpopulation, such as neurodevelopmental effects in developing embryos/fetuses and children (ATSDR, 1999)."[3]


When an agency as powerful as the FDA holds a scientific position, who can stand up to them? The truth is that many scientists outside the US and the sphere of immediate influence of the ADA and FDA disagree.

What follows below is an abstract from an article published in the German Journal for Evidence and Quality in Healthcare. This is a major international medical journal and is the official publication of the German Agency for Quality in Medicine, which is a non-profit organization owned by the German Medical Association, representing 400,000 physicians. This is a straight-forward refutation of almost every significant point of contention in the dental amalgam debate:

"There are pointers to show that mercury vapour is more neurotoxic than methyl-mercury in fish. Review of recent literature suggests that mercury from dental amalgam may lead to nephrotoxicity, neurobehavioural changes, autoimmunity, oxidative stress, autism, skin and mucosa alterations or non-specific symptoms and complaints. The development of Alzheimer's disease or multiple sclerosis has also been linked to low-dose mercury exposure…Mercury levels in the blood, urine or other biomarkers do not reflect the mercury load in critical organs. Some studies regarding dental amalgam reveal substantial methodical flaws. Removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials. Summing up, available data suggests that dental amalgam is an unsuitable material for medical, occupational and ecological reasons."[4]

To sum up, this abstract says:

  • There is evidence that mercury vapor is more toxic than methylmercury, not less.
  • Testing urine for mercury levels is not a reliable method.
  • Some studies showing favorable results for the dental amalgam are seriously flawed.
  • The dental amalgam should not be used, and health improvements can be made by removal.

And is this mercury exposure "well below levels associated with adverse health effects" (1)? Here's what a journal published by Oxford University has to say about mercury exposure in the dental profession:

"These results indicate that among DAs [dental assistants] very low levels of occupational Hg° exposure are associated with increased symptoms."[5]

Many more citations and findings can be found on our pages on the chemistry of the amalgam, the effects of mercury on the body, and the risks to the unborn.


Throughout our site, we list many scientific studies and journal articles--you may notice that many of these journals are not published in the US. Many of them are published by universities in England, Germany, Sweden, and so on. These are journals as prestigious as The Lancet and universities as influential as Oxford (Toxicological Sciences, for example). This is contrary to claims that opponents of the amalgam do not have respected references.

When they are published in the US, they are published by independent foundations such as the Neurobehavioral Teratology Society whose members are nonetheless recognized leaders in institutions such as the University of Washington, etc. Another US journal willing to publish these studies is the Journal of Toxicology and Environmental Health, for example. But look closer: the journal is published by Taylor & Francis, which is based in--you guessed it--the UK.

The point is that American universities subject to the pressures of the FDA and ADA cannot afford to publish studies contradicting their policies. There are even many instances of American researchers publishing their work in journals overseas (this study was conducted by researchers from Duke, but published in Occupational Medicine, another Oxford journal).


On the FDA page defending the use of dental amalgams, the argument begins by pointing out the very true fact that the amalgam "has been used for more than 150 years in hundreds of millions of patients."[1]

What's the implication? One can hear the outrage and impatience: "How could so many dentists and scientists have been wrong for so long?" But the same could be said for many medical practices that were eventually debunked--including bloodletting and leeching. The issue here is the same as it always is when scientists refuse to change: obstinant loyalty to the status quo and most of all--Money. If the FDA--and thereby the ADA--admitted that amalgams were toxic, what kind of class action lawsuit could be brought against the millions of dentists who have installed tens of millions of amalgams? The bottom line is that the authorities will never admit their error until it is far too late for serious financial repercussions--that is, until amalgams fall out of use, and the number of patients with amalgams decreases to some insignificant number. When will this be? 50, 60, 70 years from now?

Who will lead this change?

REFERENCES - See our complete list of sources

1. FDA Amalgam About Page:

2. Lorscheider FL, Vimy MJ, Summers AO. Mercury exposure from "silver" tooth fillings: emerging evidence questions a traditional dental paradigm. FASEB J. 1995 Nov;9(14):1499-500.

3. White Paper: FDA Update/Review of Potential Adverse Health Risks Associated with Exposure to Mercury in Dental Amalgam:

4. Mutter J, Naumann J, Walach H, Daschner F. Amalgam Risk Assessment with Coverage of References up to 2005. Gesundheitswesen. 2005 Mar; 67(3):204-16.

5. Heyer NJ, Echeverria D, Bittner AC Jr, Farin FM, Garabedian CC, Woods JS. Chronic Low-Level Mercury Exposure, BDNF Polymorphism, and Associations with Self-Reported Symptoms and Mood. Toxicological Sciences 81, 354-363 (2004). doi:10.1093/toxsci/kfh220