Resistivity of amalgams still a mystery

Readers who have been visiting these newsgroups for some time may remember my assertions that there doesn't appear to be anyone anywhere
in the world who knows what the electrical resistivity of a typical dental amalgam is.
Well, my latest Google search on this topic has thrown up a paper entitled "Resistivity of Silver-Tin Amalgams", by Richard J Schnell and Ralph W Phillips of the Indiana University School of Dentistry, which was published in the Journal of Dental Research in 1964.
See:
http://jdr.iadrjournals.org/cgi/reprint/43/4/501.pdf
This paper describes experimental procedures which were carried out in order to determine the electrical resistivities of a range of dental amalgams with varying component mixtures, and the results are presented in a series of graphs.
The trouble is that these results are all wrong.
This is because the values of the resistivities of the amalgams presented are all quoted in units of "microhms per cubic centimeter". And this is not a valid unit for electrical resistivity.
The SI unit of electrical resistivity is the ohm metre - check Wikipedia at:
http://en.wikipedia.org/wiki/Resistivity
Presenting resistivity values in units of "microhms per cubic centimeter" is nonsensical. It isn't just a question of the relative size of the unit, nor the spelling of it. Resistivity is not defined as a quantity of resistance per unit volume - as the units quoted in the report imply.
In their paper, Schnell and Phillips describe how they determined their "resistivities" thus:
"From the cross-section area and length of the specimens [of amalgam] the resistivity was calculated ...."
However they do not give any detail of how this calculation was done.
The correct way to do this calculation would be to multiply the values of resistance measured for each specimen by its cross-section area, and then divide by its length - thus giving resistivity in the appropriate unit of resistance x length (that Wikipedia page is quite correct on this).
What did Schnell and Phillips do? Surely they didn't divide their resistances by BOTH the length and the cross-section area of the specimen in the mistaken belief that resistivity can be calculated as resistance per unit volume, did they?
Well the units they used suggests that they may have done this. The only way to find out would be to get hold of their resistance measurements and work it out (they are quite precise about the dimensions of the specimen size they most frequently used).
But as it is their results are completely useless and unquotable, because electrical resistivity is not quantified in "microhms per cubic centimetre".
Could this explain why these results are never quoted?
In the textbook "Restorative Dental Materials", edited by Robert G Craig and John M Powers and published by Mosby, I can find values of electrical resistivity for Human Enamel, Human Dentin, and several different types of Dental Cements - all given in perfectly appropriate (though not SI) units of ohm.cm
However, in spite of the fact that they have devoted an entire chapter of fifty pages to the properties and use of amalgam, there isn't any indication anywhere as to what the electrical resistivity of a typical dental amalgam is.
And I am therefore forced to declare that, either in spite of or perhaps even to some extent because of Schnell and Phillips dubious efforts, it still appears that there isn't anyone anywhere in the world who knows what the electrical resistivity of a typical dental amalgam is.
Keith P walsh
PS, Electrical resistivity is just one of the properties which determine the electrical behavior of a material when it is subjected to an applied electromagnetic field. And metal amalgam dental fillings continue to be placed in children's teeth.
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Rest easy The units are quite alright. They are an older form dating from the time resistivity was expressed as ohms per centimeter cube. This is not ohms/cm^3 as it is based on the resistance between two faces of a cube which is 1cm on each side. This was updated to ohms per meter cube with the same constraint (between faces of a 1m cube). However the older form is still used often as microhm-centimeters. convert microhm-cm to ohm-m 1 microhm-cm ^8 ohm-meter so now you know that Schnell and Phillips' efforts may be less dubious than your understanding of electrical concepts.
--

Don Kelly snipped-for-privacy@shawcross.ca
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Don,
Thank you for your reply.
Your proposed conversion presumes that Schnell and Phillips applied the correct calculation to their measured resisitances in the first place. And there is no way of knowing from the information provided in the published paper that this is the case.
Do you not find it odd that the ONLY reference we can find giving resistivity values for dental amalgams is a 40 year old paper where the values are expressed in archaic units?
Why don't dental materials science textbooks EVER quote this property? Neither in old units or new?
Keith P Walsh
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Keith P Walsh wrote:

Perhaps because its not important to the intended function(s) of the material?
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Bert Hickman wrote:

more to the point, wtf does it have to do with toxicology?
this is just ignorant trolling. move along. nothing to see here.
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(Medical Labs)

http://www.acnem.org/journal/12-2_december_1993/is_dental_amalgam_safe-part_1.htm
http://www.jouglimlag.co.za/Journal%20of%20Natural%20Health%20Dental%20article.pdf
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Of what importance is the electrical resistivity of amalgam?
Would higher resistivity be good, and lower resistivity bad, or would lower resistivity be good, and higher resistivity bad?
Jan Drew has posted an enormous amount of material on the toxicity of mercury from amalgam fillings. Even if we should accept all of this as being true, for the sake of argument, I still don't see that it has anything at all to do with electrical resistivity.
Olin Perry Norton
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Bert Hickman wrote:

Occam's razor suggests the simplest explanation is the most likely. In this case, the more plausible explanation (for Keith) would be that an international conspiracy has suppressed this information over decades, across national boundaries, and even extending into the old Soviet Union. There is no organization as powerful as the American Dental Association!
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Department of Chemistry University of Kentucky http://www.uky.edu /
The ADA, through state dental boards stacked with ADA members, has instigated a "gag order" preventing dentists from even mentioning to their patients that amalgams are 50% mercury. Dentists cannot state that mercury is neurotoxic and emits from amalgams and that the dental patient should consider this as they select the tooth filling material they want used. If a dentist informs a patient of these very truthful facts, he will be consider not to be practicing good dentistry and his license will be in jeopardy.
Attacking a person's freedom of speech because he is telling the truth and causing serious questions to be asked about the protocols pushed by a bureaucracy (the ADA), makes me seriously question the commitment the ADA has for the health of the American people.
The negative stand taken by many state dental boards against even informing the patients about the mercury content of amalgams and the other filling choices they have does not speak well for the organized dental profession. What medical group would give a treatment to a patient without telling them of the risks involved?
"Issued late in 1997, the FDI World Dental Federation and the World Health Organization consensus statement on dental amalgam stated: "No controlled studies have been published demonstrating systemic adverse effects from amalgam restorations.""
My first comment would be to question, "Who staffed these committees, and what percentage were connected to the ADA though the NIDCR or the FDA dental materials branch or other relationships?" We appear to have the foxes guarding the henhouse! Then I would again point out that "absence of proof is not proof of absence".
I would then ask, 'Have any controlled studies been done and if not, why not?' If the ADA dentists insist on placing amalgams in the mouth, are they not required to show it is safe, not the other way around?
Should not the ADA and others concerned push to require the FDA to prove amalgams are safe instead of totally ducking this issue. Go to the FDA dental materials web-site and try to find any evaluation of amalgam safety -- you will not succeed. The dental branch of the FDA refuses to do a safety study on amalgams, and this is shame on our government.
"The small amount of mercury released from amalgam restorations, especially during placement and removal, has not been shown to cause any adverse effects."
This increase in mercury exposure has also not been shown to be safe by proving it does not cause any adverse effects!
Are we to believe this elevated exposure to a toxic metal is good for us?
If one were in a building that caused the rise in blood/urine mercury that appears after dental amalgam removal, then OSHA would shut the building down.
In fact, no study by the ADA or NIDCR has been completed that specifically and accurately addresses this issue. Yet, the ADA leads us to believe that additional exposure to toxic mercury from these procedures is not dangerous to our health.
Mercury toxicity is a retention toxicity that builds up during years of exposure. The toxicity of a singular level of mercury is greatly increased by current or subsequent, low exposures to lead or other toxic heavy metals (12).
Therefore, the damage caused by amalgams could occur years after initial placement and at mercury levels now deemed safe by the ADA.
Our ability to protect ourselves from the toxic damage caused by exposure to mercury depends on the level of protective natural biochemical compounds (e.g. glutathione, metallothionine) in our cells, and the levels of these protecting agents is dependent upon our health and age.
If we become ill, or as we age, the cellular levels of glutathione drop and our protection against the toxic effects of mercury decreases and damage will be done.
This is strongly supported by numerous studies where rodents have been chemically treated to decrease their cellular levels of protective glutathione and then treated with mercury, always with dramatic injurious effects when compared to controls. Therefore, published science indicates that mercury toxicity is much more pronounced in infants, the very old and the very ill.
A recent NIH study on 1127 military men showed the major contributor to human mercury body burden was dental amalgams. The amount of mercury in the urine increased about 4.5 fold in soldiers with the average number of amalgams versus the controls with no amalgams. (6)
In extreme cases it was over 8 fold higher. Since the total mercury included that from diet and industrial pollution, are we to expect that this 4.5 to 8 fold average increase in mercury is not detrimental to our health? Does this indicate that amalgams are a "safe and effective restorative material"? Is the public and Congress expected to be so nave as to believe that increased exposure above environmental exposure levels is not damaging?
Then why are pregnant mothers told to limit seafood intake when mercury exposure from amalgams is much greater? Then why is the EPA pushing regulations to force the chloro-alkali plants and fossil fuel plants to clean up their mercury contributions to our environment?
Obviously, from this study most of the human exposure to mercury is from dental amalgams, not fossil fuel plants. Yet, the FDA lets the dental profession continue to expose American citizens to even greater amounts of mercury.
They do this by refusing to test amalgam fillings as a source of mercury exposure. Also, remember that the amalgam using ADA dentists are a major contributor to mercury in our water and air through mercury leaving the dental offices, and even when we are cremated.
"The ADA's Council on Scientific Affairs 1998 report on its review of the recent scientific literature on amalgam states: "The Council concludes that, based on available scientific information, amalgam continues to be a safe and effective restorative material." and "There currently appears to be no justification for discontinuing the use of dental amalgam."
What would you expect an ADA Council to say? The ADA, as evidenced in the current letter by the President of the ADA, only quotes and considers valid the published research that supports their desire to continue placing mercury containing amalgam fillings in American citizens. When were dentists trained to evaluate neurological and toxicological data and manuscripts?
What is needed is an international conference where both the pro- and anti-amalgam researchers show up and present their data in front of a world-class scientific committee. I would challenge the ADA to line up their scientists and supporters to participate in such a conference. This could be held in Washington, D.C., so the FDA officials could easily attend. Perhaps we could persuade the FDA to sponsor such a conference.
However, this is unlikely since a recent written request to have a conference to evaluate the safety of amalgams was rejected in a letter from the FDA and signed by three FDA/ADA dentists who presented the ADA line on this issue. Doesn't it seem a bit fraudulent to have FDA/ADA dentists deciding on whether or not a safety study should be done on mercury emitting amalgams being placed in human mouths with the blessing of the ADA? This does seem like a conflict in interest that Congress should address.
"In an article published in the February 1999 issue of the Journal of the American Dental Association, researchers report finding "no significant association of Alzheimer's disease with the number, surface area or history of having dental amalgam restorations."
This research was lead by a dentist, Dr. Sax. It was submitted to the J. of the American Medical Association and rejected. It was then submitted to the New England Journal of Medicine and rejected. It was then published in the ADA trade journal, JADA, that is not a refereed, scientific journal. JADA is loaded with commercial advertisements for dental products.
They even called a "press conference" announcing the release of this article! Calling a press conference for a twice-rejected publication that is to appear in a trade journal is playing politics with science at its worst!
At this press conference, two of the authors made unbelievable statements that were not supported by any of the data in the article and conflicted with numerous major scientific reports, including the 1998 NIH study (6). Some of these were high-lighted in the side-bars of the ADA publication.
I would suggest that those concerned with this article visit Medline and look at the publication records of the two individuals who made these statements. Also, look at the three earlier excellent publications in refereed journals by some of the other authors showing significant mercury levels in the brains of AD subjects compared to controls (14a,b, 15). However, put a dentist in charge of the project, and the data gets reversed!
Apply some common sense. The ancillary comments by some of the authors and the results of the JADA publication are in total disagreement with the vast majority of research published that looks at elevated mercury levels in subjects with amalgam fillings.
For example, the NIH study on military men discussed above showed a very significant elevation of mercury in the blood that correlated with number of dental amalgams (6).
Another recent publication demonstrated elevated mercury in the blood of living AD patients in comparison to age-matched controls (10). These studies clearly show that there should be increased mercury in your blood if you have amalgams and especially if you have AD and amalgams (6,10).
Does not the brain have blood in it? This makes it a total mystery as to how could the authors of the JADA article not find elevated brain mercury levels in patient with existing amalgams and/or AD. Even cadavers have brain mercury levels that correlate with the number of amalgam fillings they had on death.
Further, if you are addressing the contribution of amalgams to brain mercury and AD, wouldn't it be important to divide the AD and control subjects into those with and without existing amalgams on death? In the JADA article this was not done, and represents a major research flaw! That this was not done also arouses suspicion.
I participated in submitting a letter pointing out this flaw to editors of JADA but they refused to acknowledge the letter and did not publish our comments. It is my opinion that the entire situation around this singular supportive publication of the ADA position on amalgams, brain mercury levels and AD represents a weak attempt at controlling the mind-set of well-meaning dentists, scientists, physicians and medical research administrators.
It definitely impedes honest scientific debate. It also explains the cavalier attitude of the ADA and NIDCR about elemental mercury exposure and toxicity, when compared to the more serious approaches taken by the EPA and OSHA.
With regards to the JADA article summary that "no statistically significant differences in brain mercury levels between subjects with Alzheimer's disease and control subjects." Here I must quote Mark Twain on honesty, "There are liars, damned liars and statisticians."
Comparing the level of mercury in the AD versus control alone using straight-forward statistics previously showed a significant difference on mercury levels in AD versus control subjects (14a,b, 15). However, there are anomalies, confounders and other factors that can be considered in this situation, especially if you don't like the initial results.
This allows one to invoke a Bon-Feroni statistical manipulation. With Bon-Feroni you include the comparison of one pair of data (that may be statistically significantly different taken alone, e.g. mercury levels in the brains of AD versus control subjects) with several other pairs of data, rendering the difference statistically insignificant.
One known weakness of the Bon-Feroni treatment of several coupled pairs of comparisons is that one very likely will miss a single comparison that is significantly different, and clever people know this. It is my opinion that application of the Bon-Feroni manipulation is what happened in this JADA study that reversed the previous significance of the mercury levels in AD versus control brain previously reported.
Research previously reported by some of the very same researchers involved in the JADA study consistently indicated that mercury levels were higher in AD versus age-matched control brains (14a,b, 15).
Only when an ADA dentist became involved, did the results change to being insignificant.
I think the data used in this JADA article and funded by NIH needs to be re-evaluated by a different statistician, if we are to ever really know if the mercury levels in the AD brains differed significantly from controls.
The letter from the ADA President then lists four publications as proof of amalgams having no statistically significant negative effects. Two of these were published in Scandinavian Journals, another was a review of the literature in a Dental Journal, and one was the JADA article mentioned above.
Sweden is well known to have led the world in the restriction and replacement of dental amalgams with non-mercury containing materials.
Forces are pushing hard to get the use of amalgams accepted again in Sweden to eliminate this embarrassment to our ADA. The current situation in Sweden and some other European countries, Canada and Japan seriously questions the ADA contention of amalgam safety. What if people in Sweden become healthier without amalgams?
Additionally, the studies quoted by the ADA President were epidemiological studies. These are very complex ,as many confounders are included which make finding a statistically significant difference very difficult.
So the results are negative, nothing found, and not surprising. However, they are in disagreement with numerous other similar reports and appear to be hand-selected to support the ADA position. One has to wonder, since the ADA President seemed to visit Swedish journals to support the ADA position, how he missed the research of the Nylander group in Sweden that showed increased mercury content in brains and kidneys of humans in relationship to exposure to dental amalgams (17,18).
Also, the referenced studies in the ADA letter did not involve neurotoxicity, autism or neurological disease -- which is the question at hand. Rather, they addressed fertility, reproduction and other systemic illnesses. Could not the ADA find references to focus on neurotoxiological studies?
What about the 1989 study that showed elevated levels of mercury in 54 individuals with Parkinson's disease when compared to 95 matched controls (16)? Further, one ought to consider who was doing these touted ADA studies and any vested interest they may have in the outcome.
I am also aware of studies done in the U.S.A. by major research universities that would disagree with the conclusions drawn by the ADA on this subject, yet these articles are not considered in the ADA letter.
At the end of the last publication the quote "Conclusions: No statistically significant correlation was observed between dental amalgam and the incidence of diabetes, myocardial infarction, stroke, or cancer."
How does this relate to an article published in the J. of the American College of Cardiology where the mercury levels in the heart tissue of individuals who died from Idiopathic Dilated Cardiomyopathy (IDCM) contained mercury levels 22,000 times that of individuals who died of other forms of heart disease? Where did this tremendous amount of mercury come from?
Even a Bon-Feroni manipulation could not make this difference insignificant! Many who die of IDCM are well-conditioned, young athletes who drop dead during sporting events -- and they live in locations and in economic environments where sea-food is not a dietary mainstay. Perhaps the victims of IDCM are within the ADA Presidents "handful of individuals who are allergic to one of its components."
"The National Institute of Dental and Craniofacial Research is currently supporting two very large clinical trials on the health effects of dental amalgam. Studies underway for several years each in Portugal and the Northeastern United States involve not only direct neurophysiological measures but also cognitive and functional assessments."
Do we really think that the NIDCR and associated ADA personnel are going to deliver up a conclusion to American parents saying "we put a mercury containing toxic material in your child's mouth that lowered his/her I.Q. and made him more susceptible to neurological problems in comparison to the children whom we selected to not get exposed to this toxic material"?
It is my opinion that most bureaucracies don't have a brain or a heart, but they do have a very strong survival instinct. Therefore, the results presented from this study will likely follow previously ADA supported research, i.e. no significant results.
Since the NIDCR started this project only 4 years ago, one has to ask why it took so long for them to get involved since the "amalgam wars" have been going on for scores of years? Was it the overwhelming amount of modern science showing mercury from amalgams being a major part of the daily exposure that forced their hand, and they had to develop a defense?
Would I trust the conclusions of this study without knowing who put it together and who did the statistics? Not any more than I trust the conclusions of the JADA article mentioned in the ADA letter that stupendously concludes that mercury from dental amalgams does not get into the brain.
As was proven by the tobacco situation, trying to find any significant negative effect of one product (amalgams) related to any disease through epidemiological studies is very difficult and complex. To do this with mercury would be difficult because of the synergistic effect two or more toxic metals or compounds (e.g. cadmium from smoking) may have on the toxicity of the mercury emitted from amalgams.
For example, one publication showed that combining mercury and lead both at LD1 levels caused the killing rate to go to 100% or to an LD100 level (12). An LD1 level is where, due to the low concentrations, the mercury or the lead alone was not very toxic alone (i.e., killed less than 1% of rats exposed when metal were used alone).
The 100% killing, when addition of 1% plus 1% we would expect 2%, represents synergistic toxicity. Therefore, mixing to non-lethal levels of mercury plus lead gave an extremely toxic mixture! What this proves is that one cannot define a "safe level of mercury" unless you absolutely know what others toxicants the individual is being exposed to.
The combined toxicity of various materials, such as mercury, thimerosal, lead, aluminum, formaldehyde, etc., is unknown. The effects various combinations of these toxicants would have is also not defined, except that we know they would be much worse than any one of the toxicants alone.
So, how could the ADA take any exception, based on intellectual considerations, to my contention that combinations of thimerosal and mercury could exacerbate the neurological conditions identified with autism and AD?
Autism and AD have clinical and biological markers that correspond to those observed in patients with toxic mercury exposure.
Why would the ADA take this position? I personally feel like I have been in a ten year argument with the town drunk on this issue. Facts don't count, and data is only valid if it meets the pro-amalgam agenda.
The ADA was founded on the basis that mercury-containing amalgams are safe and useful for dental fillings. This may have been an acceptable position in 1850. However, modern science has proven that amalgams constantly emit unacceptable levels of mercury.
Especially, as the average life span has increased from 50 to 75-78 years of age, where AD and Parkinson's become prevalent diseases. The ADA can try to verify its position, using selected epidemiological studies. But the bottom line is that amalgams emit significant levels of neurotoxic mercury that are injurious to human health and would exacerbate the medical condition of those individuals with neurological diseases such as ALS, MS, Parkinson's, autism and AD.
I am hoping that the ADA sent this letter to your committee and also placed it on the ADA web-site to indicate that they are now willing for a wide-open discussion to take place on the issue of dental amalgams.
I, for one, would welcome a major scientific conference on this issue. The ADA should feel free to post my letter in response and address any issue they feel that I am mistaken about.
However, in closing, I urge your Committee to push forward on the study of the potential dangers of mercury in our dentistry and medicines. This includes mercury exposures from amalgams, vaccines and other medicaments containing thimerosal. The synergistic effects of mercury with many of the toxicants commonly found in our environment make the danger unpredictable and possibly quite severe, especially any mixture containing elemental mercury, organic mercury and other heavy metal toxicants, such as aluminum.
Sincerely, Boyd E. Haley Professor and Chair Department of Chemistry University of Kentucky
http://www.mercola.com/2001/jun/9/amalgam_safety3.htm References: (Part 1, Part 2) 1. a. Duhr, E.F., Pendergrass, J. C., Slevin, J.T., and Haley, B. HgEDTA Complex Inhibits GTP Interactions With The E-Site of Brain b-Tubulin Toxicology and Applied Pharmacology 122, 273-288 (1993).; b. Pendergrass, J.C. and Haley, B.E. Mercury-EDTA Complex Specifically Blocks Brain b-Tubulin-GTP Interactions: Similarity to Observations in Alzheimer's Disease. p 98-105 in Status Quo and Perspective of Amalgam and Other Dental Materials (International Symposium Proceedings ed. by L. T. Friberg and G. N. Schrauzer) Georg Thieme Verlag, Stuttgart-New York (1995).; c. Pendergrass, J.C. and Haley, B.E. Inhibition of Brain Tubulin-Guanosine 5'-Triphosphate Interactions by Mercury: Similarity to Observations in Alzheimer's Diseased Brain. In Metal Ions in Biological Systems V34, pp 461-478. Mercury and Its Effects on Environment and Biology, Chapter 16. Edited by H. Sigel and A. Sigel. Marcel Dekker, Inc. 270 Madison Ave., N.Y., N.Y. 10016 (1996).
2. Pendergrass, J. C., Haley, B.E., Vimy, M. J., Winfield, S.A. and Lorscheider, F.L. Mercury Vapor Inhalation Inhibits Binding of GTP to Tubulin in Rat Brain: Similarity to a Molecular Lesion in Alzheimer's Disease Brain. Neurotoxicology 18(2), 315-324 (1997).
3. David, S., Shoemaker, M., and Haley, B. Abnormal Properties of Creatine kinase in Alzheimer's Diseased Brain: Correlation of Reduced Enzyme Activity and Active Site Photolabeling with Aberrant Cytosol-Membrane Partitioning. Molecular Brain Research 54, 276-287 (1998).
4. Leong, CCW, Syed, N.I., and Lorscheider, F.L. Retrograde Degeneration of Neurite Membrane Structural Integrity and Formation of Neurofibillary Tangles at Nerve Growth Cones Following In Vitro Exposure to Mercury. NeuroReports 2 (4): 733-737, 2001.
5. Olivieri, G., Brack, Ch., Muller-Spahn, F., Stahelin, H.B., Herrmann,
M., Renard, P; Brockhaus, M. and Hock, C. Mercury Induces Cell Cytotoxicity and Oxidative Stress and Increases b-amyloid Secretion and Tau Phosphorylation in SHSY5Y Neuroblastoma Cells. J. Neurochemistry 74, 231-231, 2000.
6. Kingman, A., Albertini, T. and Brown, L.J. Mercury Concentrations in Urine and Whole-Blood Associated with Amalgam Exposure in a U.S. Military Population. J. Dental Research 77(3) 461-71, 1998.
7. Chew, C. L., Soh, G., Lee, A. S. and Yeoh, T. S. Long-term Dissolution of Mercury from a Non-Mercury-Releasing Amalgam. Clinical Preventive Dentistry 13(3): 5-7, May-June (1991).
8. Hahn, L.J., Kloiber, R., Vimy, M. J., Takahashi, Y. and Lorscheider, F.L. Dental "Silver" Tooth Fillings: A Source of Mercury Exposure Revealed by Whole-Body Image Scan and Tissue Analysis. FASEB J. 3, 2641-2646, 1989.
9. Hahn, L.J., Kloiber, R., Leininger, R.W., Vimy, M. J., and Lorscheider, F.L. Whole-body Imaging of the Distribution of Mercury Released from Dental Filling Into Monkey Tissues. FASEB F. 4, 3256-3260, 1990.
10. Hock, C., Drasch, G., Golombowski, S., Muller-Span, F., Willerhausen-Zonnchen, B., Schwarz, P., Hock, U., Growdon, J.H., and Nitsch, R.M. Increased Blood Mercury Levels in Patients with Alzheimer's Disease. J. of Neural Transmission v105(1) 59-68, 1998.
11. Frustaci, A., Magnavita, N., Chimenti, C., Caldarulo, M., Sabbioni, E., Pietra, R., Cellini. C., Possati, G. F. and Maseri, A. Marked Elevation of Myocardial Trace Elements in Idiopathic Dilated Cardiomyopathy Compared With Secondary Dysfunction. J. of the American College Cardiology v33(6) 1578-1583, 1999.
12. Schubert, J., Riley, E.J., and Tyler, S.A. Combined Effects in Toxicology-- A Rapid Systemic Testing Procedure: Cadmium, Mercury and Lead. J. of Toxicology and Environmental Health v4, 763-776,1978.
13. Wataha, J. C., Nakajima, H., Hanks, C. T., and Okabe, T. Correlation of Cytotoxicity with Element Release from Mercury and Gallium-based Dental Alloys in vitro. Dental Materials 10(5) 298-303, Sept. (1994)
14. a. Ehmann, W., Markesbery, W., and Alauddin, T., Hossain, E. and Brubaker, E., Brain Trace Elements in Alzheimer's Disease. Neurotoxicology 7(1) p197-206, 1986. b. Thompson, C. M., Markesbery, W.R., Ehmann, W.D., Mao, Y-X, and Vance, D.E. Regional Brain Trace-Element Studies in Alzheimer's Disease. Neurotoxicology 9, 1-8 (1988).
15. Wenstrup, D., Ehmann, W., and Markesbery, W. Brain Research, 533, 125-131, 1990.
16. Ngim, C.H., Devathasan, G. Epidemiologic Study on the Assocaiation Between Body Burden Mercury Level and Idiopathic Parkinson's Disease. Neuroepidemiology, 8, 128-141, 1989.
17. Nylander, M., Friberg, L. and Lind, B. Mercury Concentrations in the Human Brain and Kidneys in Relation to Exposure from Dental Amalgam Fillings. Swedish Dentistry J. 11:179-187, 1987.
18. Nylander, M., Friberg, L., Eggleston, D., Bjorkman, L. Mercury Accumulation in Tissues from Dental Staff and Controls in Relation to Exposure. Swedish Dental J. 13, 235-243, 1989
19. Heintze, U. Edwardsson, S., Derand, T. and Birkhed, D. Methylation of Mercury from Dental Amalgam and Mercuric Chloride by Oral Streptococci in vitro. Scand. J. Dental Research 91(2) 150-152, 1983.
http://www.mercola.com/2001/jun/9/amalgam_safety.htm Part 1/2 *********************************************************
DR. MERCOLA'S COMMENT: Dr. Boyd Haley is clearly one of the top US researchers in the area of scientifically documenting the dangers of mercury. His letter refutes the American Dental Association (ADA) response to his April 25, 2001 congressional testimony on mercury.
Related Articles:
http://www.mercola.com/article/mercury / Mercury Detoxification Protocol
http://www.mercola.com/2001/apr/7/vaccine_mercury.htm First Mercury Poisoning/Vaccine Law Suit Filed
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Disclaimer - Newsletters are based upon the opinions of Dr. Mercola. They are not intended to replace a one-on-one relationship with a qualified health care professional and they are not intended as medical advice. They are intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. **************************************************************
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As long as the method that Schnell and Phillips used in calculating the resistivities from their resistance measurements was consistent then one thing that their results show is that the resistivity of dental amalgam varies significantly with variations in the proportions of the components of the amalgam, both in terms of the percentages of the constituent metals in the solid alloy, and in terms of the proportions of solid alloy to liquid mercury used in the mix.
This is hardly a surprise. Indeed, judging from the degree of variation it might be argued that in this respect no two amalgam mixes are ever exactly the same, and therefore no two amalgams ever have exactly the same electrical resistivity profile.
Is it possible that this may explain why only a small proportion of the people who have ever had amalgam fillings placed in their teeth have reported hearing radio signals from them?
Amalgam fillings are not placed in people's teeth in order to attenuate radio signals. That is to say, this is not their "intended function".
However, amalgam fillings are not exempt from the laws of nature.
Do you think it would be possible to devise an experimental procedure to determine which frequencies of electromagnetic signals are not attenuated by amalgam fillings?
And if so, would you expect that the same procedure could be used to demonstrate which frequencies, if any, are?
Would you expect the electrical resistivity of the amalgams to have any bearing on the results?
Keith P Walsh
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Or, only a small proportion of the people who have ever had amalgam fillings have the specific conditions required to form a non-linear junction AND are close enough to a transmitter for a signal to be detected.

What does "attenuated" have to do with anything?
I suggest you look up the meaning of "attenuated".
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Jim Pennino

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If you don't like their numbers, make the measurement yourself.
People have volunteered to send you the amalgam.
People have told you how to make the measurements.
I personally went so far as to find the equipement required at a reasonable cost and offered to pay for it if you would publish the results.
Your response has been to continue to whine for years now that no one is making these measurements.

Once it is measured, it is measured.
How often should it be remeasured? Once a decade, once a year, every day?

Because no one except babbling, insane, kooks like yourself thinks it is relevant to anything.
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Jim Pennino

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On 10 Jun, 16:35, snipped-for-privacy@specsol.spam.sux.com wrote:

Why didn't you ever refer me to Schnell and Phillps' paper?
Keith P Walsh
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Because I think someone who obsesses on the electrical properties of amalgam is a lunatic and not worth the waste of time to search for such a paper.
If you think it is so important, why didn't you ever make the measurements yourself?
After all, they are putting this stuff into children, don't you care about children?
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Jim Pennino

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----------------------------
wrote:

------------------- Possibly they don't quote it because it is not important. What is likely of more importance is a combination of several factors including filling size and surface contact resistance behaviour, etc- things that cannot be determined because there are too many unknown and uncontrollable factors to consider. Resistivity of the filling is an unlikely suspect. Rectification at surface boundaries may be much more of a problem.
--

Don Kelly snipped-for-privacy@shawcross.ca
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Don,
Thank you again for your contribution. I may be wrong but I suspect that you are not a dentist. Most dentists in these newsgroups appear only able to respond to any suggestion that metal amalgam dental fillings might absorb and dissipate electromagnetic energy to their surroundings with both ridicule and derision - as if they have been led to believe that dental fillings are in some way exempt from the laws of nature.
Also in my experience, people often appear inclined to assume that amalgams are comparable to common alloys with regard to their physical properties.
But in fact the internal structure of an amalgam, such as a typical dental amalgam, differs from that of a true alloy most significantly in that amalgams exhibit a much greater degree of material inhomogeneity.
You can see a representation of the microstructure of a typical dental amalgam at:
http://book.boot.users.btopenworld.com/setting.htm
A large proportion of the material is made up of particles, or inclusions, of the solid alloy used in the amalgam mix which have not reacted with any mercury at all. These inclusions are held together by a solidified matrix which is of a dissimilar metallic composition and which is formed by the action of the liquid mercury on the outer surfaces only of the solid alloy particles.
I would expect that the electrical resistivity of such an amalgam should vary more significantly from point to point within the material than that of a true alloy. I would also suggest that the values of the resistivities determined by Schnell and Phillips might only represent the "bulk" property for the material, and that they do not appear to have attempted to determine the degree of variation of the electrical resistivity within in their samples.
Would you agree?
Do you think that the inhomogeneous nature of dental amalgams could have any influence on the tendency for amalgam dental fillings to "rectify" signals - which you have implied above may exist?
Would you be able to suggest an experimental procedure to determine whether or not this does in fact happen?
Best regards,
Keith P Walsh
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----------------------------
wrote:

In other words, the amalgam may act as a "crystal set" independent of resistivity but dependent on inhomogenity. So- how do you prove it? in vitro-maybe, maybe not,- otherwise still a question mark. Testing? that means replication of conditions under controlled conditions. First establish the conditions and then try to replicate them. How do you then find a signal? Cat's whisker as in a crystal set (and the somewhat bulky coil and capacitor tuning that goes with that but not in vitro) What you are looking for is a strong enough incoming signal to get the "rectification" needed and also to somehow couple this to auditory nerves. Apparently possible but the question is how much harm is produced? My own opinion is that while it may be annoying to the sensitve who may have other problems, it is negligable.
No, I am not a dentist- just as you are not an engineer. I doubt whether either of us know enough about nerve systems to give any reasonable answer.
--

Don Kelly snipped-for-privacy@shawcross.ca
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Don,
You're wrong. I am an engineer, although I do not specialise in electronics (nor in archaic systems of units).
I am also a scientist, and I'll prove it to you.
Metal amalgam dental fillings are placed in children's teeth. There isn't an experimental investigation into any aspect of the electrical and/or electromagnetic behavior of amalgams that either you or I can think of which should not therefore already have been carried out.
And the results should be available.
Keith P Walsh
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Sanitation engineer?

Yeah, right.

All this proves is you're incapable of logical thinking.

Bubble gum is placed in children's mouths. There isn't an experimental investigation into any aspect of the electrical and/or electromagnetic behavior of bubble gum that either you or I can think of which should not therefore already have been carried out.
And the results should be available.
--
Jim Pennino

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snipped-for-privacy@specsol.spam.sux.com wrote:

mercury sure ain't bubble gum, and amalgams release a lot of merucury. Since resistance IS derived from the basic material properties of amalgam it iS ultimately relevant to understanding the toxicity of amalgam.
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