What's Wrong with the October 2003
NEJM Article on Mercury?


The New England Journal of Medicine October 30, 2003 issue featured an article entitled "The Toxicology of Mercury-Current Exposures and Clinical Manifestations" by Clarkson, Magos and Myers. You can download the article by going to www.scholar.google.com and typing in the title of the article or clicking on the link below. Be sure to print a copy of the article and then read the comments below where Bernard Windham critiques the flaws in this article.

The Toxicology of Mercury-Current Exposures and Clinical Manifestations

Why am I interested in your reading this NEJM article? Because pro mercury dental organizations are already using this article published in a prestigious publication to support their fallacy that mercury amalgam fillings are safe. Dentists will surely quote this article to their patients without even bothering to read the article indepth or with a critical mind. If you only listen to the ADA's spin on the science you will never know the truth.

Bernard Windham, President and Scientific Coordinator for DAMS (Dental Amalgam Mercury Solutions), whose website can be accessed at http://www.dentaltruth.org critiqued this October 30, 2003 NEJM article and exposed its scientific flaws.



By Bernard Windham:
Taken from

The Clarkson, Magos, Myers mercury article in NEJM, Oct 30, 2003 is very poorly done with a lot of inaccuracies, misstatements, and poor research. The following provides documentation for some examples of such inaccuracies affecting important issues. Summary fact sheets (with URLs) citing peer-reviewed studies and clinical results are mostly used in this regard, because listing all the references here would make this review extremely long. There are over 1000 peer-reviewed studies referenced, supporting the premise of the fact sheets, which are contrary to the statements in the authors' paper.

On page 1731 they write: "Fish are main if not the only source of methyl mercury" and on page 1733 that "among humans, the sole source of exposure to methyl mercury is the consumption of fish and sea mammals."

This is wrong and contrary to research and clinical experience. People with no exposure to fish or sea mammals can easily be found by test to have significant levels of methyl mercury in the blood, saliva, and brain, etc. if they have exposure to other forms of mercury. Dental amalgam is documented to be the largest source of mercury in most people; and other forms of mercury are methylated in the body by bacteria, yeast, and other methyl donors- making amalgam the largest source of methyl mercury in many. There is a lot of documentation available:

In Table 1:

Under mercury vapor they donít point out that dental amalgam is the largest source of mercury vapor in most and that the studies that they show arenít relevant to this exposure. There is a huge amount of documentation regarding the common adverse health effects from exposure due to dental amalgam including over 60,000 clinical cases of recovery from over 30 chronic conditions after amalgam replacement. Documentation is available at They donít mention that thimerosal/ethyl mercury are documented to be a major cause/factor of autism, ADHD, eczema, etc. or discuss the evidence - documentation at They state that chelation is not effective for methyl mercury and ethyl mercury poisoning; which is contrary to evidence and experience: For ethyl mercury: and extensive other clinical experience and studies from NIH Medline for methyl mercury.

The fact that some people with acute exposures are irreparably harmed doesnít warrant blanket statements that chelation isnít effective in general. Thousands are treated with positive results by doctors throughout the country each year by many variations of what would be called chelation or detoxification. Since the mercury forms: vapor, inorganic, organic are being converted back and forth continuously in the body, one canít neatly split exposure and treatment results between forms- though there are known differences in general effects and mechanisms of actions of the different forms.

On page 1732 they state wrongly regarding mercury exposure from amalgam that: "it was realized that the actual inhaled dose was small, due to the small volume of the oral cavity."

This statement is strange since they go on to say dental amalgam is the chief source of exposure to mercury vapor for most. But the fact is that the exposure isnít small but rather very large and more than the federal health guideline level is well documented in the medical literature from the many studies of mercury excretion in those with amalgam(some of which they later quote). Perhaps the problem is that these researchers do not have experience diagnosing and treating mercury toxicity and are not aware of what it means to talk of a small exposure in something so extremely toxic as mercury. See And the fact is that all sewers and sewer sludge have high (and dangerous levels of mercury) with the largest source being from dental amalgam (dental offices and excretion of those with amalgam). They have a typo in the reference they quote on level of exposure to mercury from amalgam on page 1732. (It should be 5 rather than 8.)

On page 1733 they state:
"Todayís occupational exposures, such as in the dental office are lower and may lead to mild, reversible effect on the kidney or mild cognitive changes and memory loss."

They site only one fairly old reference that didnít focus on this issue (though it was a good review), even though there are hundreds of studies and clinical investigations that document significant neurological, reproductive, cognitive, and immune effects of dental office exposures.

Mark Richardson of Health Canada has estimated that about 20% of the population suffers a subclinical impairment of kidney or CNS function related to amalgam mercury.

There is solid documentation that those with dental office exposures have exposures and body burdens much higher than those patients with amalgam fillings on average, and that in the long term adverse effects are common. On page 1733 they state that "current evidence shows no connection" for a link between chronic mercury exposure and chronic neurological or autoimmune conditions such as Alzheimerís, multiple sclerosis, Parkinsonís, etc. In fact there is no solid evidence supporting their statement. They donít fully review the literature and clinical experience, which is extensive, and cite only 3 studies which they say agree with their position. The main study they cite, the nun study, is known to have serious methodological flaws including no valid control population or measurements of body burden which caused it to not be published by a scientifically peer reviewed journal.

Another study used serum blood mercury level to judge body burden, which is well documented to not be reliable for this purpose. None of the studies used reliable measures of body burden, nor did they bother to measure any of the susceptibility measures such as ability to excrete mercury or immune reactivity, which are documented in the literature to be the major factors in who is adversely affected my mercury exposure. The authors didnít bother to review the many hundreds of studies which document the mechanisms by which mercury causes the conditions seen in Alzheimerís, Parkinsonís, multiple sclerosis, chronic fatigue, fibromyalgia, lupus, Lou Gehrigís Disease, etc. or the thousands of cases of recovery or significant improvement from these conditions after treatment for mercury toxicity: Regarding their statements on page 1733 discouraging replacement of amalgam fillings, they donít bother to point out that when amalgam fillings are replaced the increased exposure is temporary and limited where properly done (as documented in the literature) and that daily exposure levels are reduced 60 to 90 percent in the long run (as documented in the literature) or that peer reviewed studies and clinical studies document that thousands have recovered or had significant improvement from serious chronic conditions after amalgam filling replacement.

Their statement that "there is no clear evidence supporting the removal of amalgams" is obviously wrong and irresponsible, since many peer-reviewed studies have documented conditions where most who have amalgams replaced recover, and thousands are documented to have recovered from over 30 chronic conditions. On page 1735 the authors in dealing with prenatal exposure focus attention and limit discussion to methyl mercury. But it is well documented in the literature that adverse developmental effects are more common and occur at lower levels for mercury vapor exposure (as from dental amalgam) than for methyl mercury. For example it is well documented that prenatal exposure to thimerosal (rhogam shots) and dental amalgam from mothers are major factors in causation of autism and other childrenís neurological developmental conditions.
On page 1735 the authors state that "it is reassuring that the only clinical reports of mercury poisoning from fish consumption are those from Japan in the 1950s and 1960s," and "the risk posed by exposure to mercury is currently speculative." Iím not sure why they would have stated this since there are extensive and well publicized studies and reports as well as Government panel conclusions of adverse effects all over the world from mercury exposure through eating fish and marine mammals that eat fish.

  • J.T. Salonen et al, "Intake of mercury from fish and the risk of myocardial infarction and cardiovascular disease in eastern Finnish men", Circulation, 1995; 91(3):645-55;
  • Wisconsin Bureau of Public Health, Imported seabass as a source of mercury exposure: a Wisconsin Case Study, Environ Health Perspect 1995, 103(6): 604-6;
  • Watanabe KH, Desimone FW, Thiyagarajah A, Hartley WR, Hindrichs AE. Fish tissue quality in the lower Mississippi River and health risks from fish consumption. Sci Total Environ. 2003 Jan 20;302(1-3):109-26.;
  • J. Hightower, "Methylmercury Contaminmation in Fish: Human Exposures and Case Reports," Environmental Health Perspectives; Nov 1, 2002;
  • A Oskarsson et al, Swedish National Food Administration, Mercury levels in hair from people eating large quantities of Swedish freshwater fish. Food Addit Contam 1990; 7(4):555-62;
  • Preventive Medicine February 2002;34:221-225;
  • Dickman MD; Leung KM, "Hong Kong subfertility links to mercury in human hair and fish", Sci Total Environ, 1998,214:165-74;
  • Mercury and organochlorine exposure from fish consumption in Hong Kong. Chemosphere 1998 Aug;37(5):991-1015;
  • Y.Kinjo et al, "Cancer mortality in patients exposed to methyl mercury through fish diet", J Epidemiol, 1996, 6(3):134-8;
  • Choy C et al, Seafood consumption linked to infertility, BJOG: An International Journal of Obstetrics & Gynaecology 2002 109:1121-5;
  • http://www.flcv.com/flhg.html
  • http://www.flcv.com/damspr16.html
On page 1735 the authors quote the Seychelles study as an example of study that found no adverse effects from eating seafood. However they donít point out that it is well documented that the main assumptions in that study were faulty and incorrect. They did no control for other significant mercury exposures and excluded from the study those who experienced conditions like epilepsy that are known to be caused by mercury toxicity. They did not measure or take known susceptibility factors into account even though these are documented to be significant in mercury effects(see later discussion). Their main measure of mercury toxicity or exposure was hair level, which is known for those who are affected most by mercury exposure/toxicity to be inversely proportional to body burden and health effects- the opposite from the authors assumptions- and which led to seemingly strange results. (See following discussion for reference.)

[The following paragraph is snipped from http://flcv.com/kidshg.html which has the references:]

A recent study found that prenatal mercury exposures and susceptibility factors such as ability to excrete mercury appear to be a major factors in those with chronic neurological conditions like autism (86). Infants whose mothers received prenatal Rho D immunoglobulin injections containing mercury thimerosal or whose motherís had high levels of amalgam fillings had a much higher incidence of autism. While the hair test levels of mercury of infants without chronic health conditions like autism were positively correlated with the number of the motherís amalgam fillings, vaccination thimerosal exposure, and mercury from fish, the hair test levels of those with chronic neurological conditions such as autism were much lower than the levels of controls and those with the most severe effects had the lowest hair test levels, even though they had high body mercury levels. This is consistent with past experience of those treating children with autism and other chronic neurological conditions(23).

Very low levels of exposure have been found to seriously affect relatively large groups of individuals who are immune sensitive to toxic metals(11,35), or have an inability to detoxify metals due to such as deficient sulfoxidation or metallothionein function(18,36,51) or other inhibited enzymatic processes related to detoxification(15-24,30) or excretion of metals(87). Those with the genetic allele ApoE4 protein in the blood have been found to detox metals poorly and to be much more susceptible to chronic neurological conditions than those with types ApoE2 or E3(87).]

Note that while hair test mercury level is not a reliable indicator of mercury body burden or mercury toxicity effects in those susceptible to mercury toxicity effects, the hair test results are useful in indicating those with mercury toxicity(23e). Since mercury toxicity affects cell membrane permeability and essential mineral absorption and cellular balance, a pattern of essential mineral imbalances in those with normal diets is an indicator of mercury toxicity.

The last section of the paper on thimerosal effects is poorly researched. They state again that "methyl mercury is more potent" than other forms, which is not supported by scientific evidence, as previously seen. All of the forms are extremely toxic and no categorical statement can be supported of this nature. Studies in the previously referenced papers on thimerosal/vaccine effects document that ethyl mercury has toxicity effects of similar magnitude as methyl mercury, and that mercury vapor exposure has developmental effects at lower levels of exposure than methyl mercury. The authors state that since the half life of ethyl mercury in the blood is less than that of methyl mercury, "risks of its damaging either the brain or kidneys would seem remote." However there is no scientific evidence supporting this conclusion and no plausible explanation of why they would think so. Besides the fact that the conclusion of shorter half life in the blood does not imply that body burden is less or decreased, as seen in the previously referenced paper by Haley, Holmes, Blaxill; having a shorter half life in the blood has no proven significance in the degree of developmental damage by a highly toxic neurologic substance. Mercury vapor, which has a far shorter half life in the blood, than the other 2 forms, has the most developmental effects at lower levels of exposure.


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