MERCURY FILLINGS FILLINGS: ARE THEY REALLY SAFE?

Copyright © 2006 Elmer M. Cranton, M.D.

     Mercury has always existed in the earth's crust and in the human body at safely tolerated levels. The clinical problem now is to determine the threshold of safe tolerance and the upper limits before toxicity occurs.

    Two recent studies by the University of Washington show that mercury in amalgam fillings does not cause health problems, even in young children.

Bellinger DC, Trachtenberg F, Barregard L, Tavares M, Cernichiari E, Daniel D, McKinlay S. Neuropsychological and renal effects of dental amalgam in children: a randomized clinical trial.JAMA. 2006 Apr 19;295(15):1775-83.

DeRouen TA, Martin MD, Leroux BG, Townes BD, Woods JS, Leitao J, Castro-Caldas
A, Luis H, Bernardo M, Rosenbaum G, Martins IP. Neurobehavioral effects of dental amalgam in children: a randomized clinical
trial. JAMA. 2006 Apr 19;295(15):1784-92.

     Although mercury levels in blood and urine do increase somewhat with amalgam dental fillings, toxic levels apparently do not occur. Elevated urine and hair levels merely reflect the ongoing elimination of mercury from the body by these routes.  For every known toxin there is a threshold level below which no toxicity occurs. We tested hundreds of patients for mercury over the past 10 years and have found less than five people two with significantly high levels. One had been eating a full can of solid white albacore tuna several times every day for years. In my opinion, based on years of clinical experience, toxicity from mercury is rare.

    The clinical dilemma is to determine the level at which mercury is not tolerated by the body and can cause toxic symptoms. Mercury has always been present in the earth's crust, in food, in sea water and in sea food, in tiny amounts. Advanced technology and scientific instruments are now so sensitive that everyone without exception will test positive for low levels of mercury. This is causing a bit of fear-based mass hysteria. Many illnesses of unknown cause are being mistakenly blamed on mercury. The truth probably lies somewhere in the middle.

     It is a not true that toxins are toxic at low levels. Toxicity only occurs if the level of a toxin exceeds the threshold for toxicity. There always exists a low-level threshold of safe tolerance below which a substance is non-toxic, even for mercury, lead and arsenic. That is true for all toxins, not just toxic metals, as well as for nuclear and cosmic radiation. It’s a fundamental scientific principle of toxicology.

          The "linear-toxic-effect-no-threshold" notion is untrue and unscientific. Potentially toxic metals of all types have always existed in the human body at safe, low levels. They are widespread at tiny concentrations and widely disbursed in the earth's crust, in food, in air, and in the water—they always have been, even before industrial pollution increased those levels. Every human that ever lived has been exposed to some low level of every metallic toxin. The only limitation in detection has been the sensitivity of instruments used for measurement. In recent years technology has advanced to the point that extremely low levels (parts per billion, even parts per trillion) can now be measured.  Mercury and other heavy metals is being blamed for a wide variety of diseases and chronic conditions in which they play no part.

     A small group of laboratories that market services to alternative and complementary clinics misleadingly report toxicity at very low levels of a variety of metals with no accepted scientific basis. They also often recommend giving a chelator before collecting urine, which causes in a high percentage of false positive measurements.

      To determine if measured amounts are above or below a threshold for toxicity requires objective scientific facts, derived from scientific studies and a large number of measurements on populations known to be exposed. Laboratories used by alternative practitioners often confuse the facts by setting reference ranges on their report forms so low that a very high percentage of patients tested mistakenly show up as “toxic.” That is a mistake and can cause the true diagnosis to be missed. The presence of low levels of toxic metals does not mean that they are toxic.

HOW MUCH MERCURY IS TOO MUCH?

QUESTIONS AND ANSWERS FROM THE UNIVERSITY OF ROCHESTER

How is mercury exposure measured? Scientists can determine a person's exposure to mercury (especially methyl mercury, the most toxic form) by measuring mercury content in hair. By comparing these levels to the results of very sophisticated batteries of tests, scientists try to determine the lowest level that might be harmful.

At what level does mercury become harmful? Based on scientific results from exhaustive studies of  known episodes of poisoning, the World Health Organization has placed the level at which risk begins at 50 ppm of mercury in hair  for most people.  The WHO then applied a safety factor of 10, estimating that a level of 5 or less is safe for even the most vulnerable populations. More recently the University of Rochester conducted an extensive study in the Seychelles Islands of the most sensitive population (pregnant women and their young children from birth onward) where the average hair mercury level is about 7 ppm, about 10 times the level of the U.S. population. These people ate ocean fish 12 or times or more often every week. Scientists found no harm from mercury at levels up to 15 ppm, nearly twice the average Seychelles level and about 20 times higher than the average U.S. level. Despite those reports, hair analysis laboratories in the U.S. continue to report of toxicity at only 1 ppm.

    As you can see above, it is customary for the EPA and for clinical laboratories to apply a safety factor of 10 on report forms.  If the lowest known level associated with toxicity is 50 ppm, the WHO sets the recommended range for the general public below 5 ppm. Thus, is it highly unlikely that toxicity is responsible for symptoms unless the measured level is at least 10 time the upper limit on a laboratory report form. For industrial workers who are regularly exposed to mercury on the job, OSHA sets the allowable limits much higher, closer to a proven toxic level, before removing a worker from further exposure.

     Symptoms of heavy metal toxicity are largely non-specific and non-diagnostic. Almost everyone with a chronic illness will experience symptoms similar to those caused by toxic metals. Chronic fatigue syndrome, yeast related illness, food and chemical sensitivity and other environmental exposures are often misdiagnosed as heavy metal toxicity.

          Mercury toxicity, as well as toxicity from a number of other metals, is potentially a very serious problem. Toxicity certainly does occur. Industrial pollution has greatly increased exposure in recent times. It is important, however,  to cut through unscientific misinformation and arrive at an accurate assessment of whether metal toxicity is really the problem and if treatment with a chelator is indicated for a specific patient. Metallic toxins are continuously eliminated from the body with no treatment at all and levels remain safe and low if excessive exposure is avoided.

       Scientific research shows that once a source of excessive mercury exposure is eliminated, half of the remaining mercury in the body is excreted naturally in less than 3 months, with no treatment whatsoever. Even methyl mercury is naturally eliminated from the brain. Mercury is eliminated normally in urine, feces, hair, skin, sweat, bile, etc. One year after excessive exposure has been eliminated, 95 percent or more of the excess mercury is gone from the body with no specific treatment. That fact is often ignored. Mercury chelators merely speed up a process that occurs naturally with no treatment. EDTA chelation has no effect on methyl mercury. (If high exposure to methyl mercury causes brain damage, removal of the mercury does not reverse that damage, but does prevent further harm.)

       The biggest challenge is to seek out the source of a potentially toxic exposure to metals and minimize it. Even eating ocean fish on a daily basis is not enough to cause toxic mercury levels. A recent study by the University of Rochester in the Seychelles Islands showed that eating ocean fish an average of 12 meals per week did not cause toxic levels of mercury, even in pregnant women and small children.

Myers GJ, Davidson PW, Cox C, Shamlaye CF, Palumbo D, Cernichiari E, Sloane-Reeves J, Wilding GE, Kost J, Huang LS, Clarkson TW. Prenatal methylmercury exposure from ocean fish consumption in the Seychelles child development study. Lancet. 2003 May 17;361(9370):1686-92.

      In summary, low levels of mercury can be safely tolerated and some level of mercury has always been present in everyone on earth and in the human body. There exists a threshold level below which mercury is well tolerated without toxic effects. Low levels of mercury are normally found in food and water because it is widely distributed in the earth’s crust in tiny amounts.

     Some alternative medicine doctors are using the injectable drug DMPS to remove mercury. It does remove the metal from many parts of the body, but unlike DMSA, it does not remove mercury as well from the brain. The most important toxic effects of mercury are in the brain, so an agent like DMSA, that removes mercury from the brain and can conveniently be taken by mouth is the treatment of choice. DMSA is more convenient, less expensive, safer and more effective than DMPS for mercury detoxification. It is even approved by the FDA for use in children. DMPS is quite toxic for some people.

Click on the link below to read about DMSA research:

DMSA by Mouth, the Treatment of Choice for Mercury Toxicity

Click on the links below for information on toxicity of DMPS:

www.dmpsbackfire.com/default.shtml

www.tldp.com/issue/175-6/DM.html

     Despite the  low risk, I recommend that if dental fillings are needed, ask your dentist to restore your teeth without the use of mercury. That is only common sense. On the other hand, replacing a large number of amalgam fillings in a short time can make symptoms worse because of the various chemicals and resins used—some of which are potentially more toxic than mercury when exposure is high.

REFERENCES:

1) Gay DD, Cox RD, and Reinhard JW. "Chewing Releases Mercury from Fillings". Lancet, May 5, 1979.
2) O’Carroll RE, Masterson G, Dougall N, et al. "The neuropsychiatric sequelae of mercury poisoning -- The mad hatter’s disease revisited". British Journal of Psychiatry. 1995;67: 95-98.
3) Eggleston DW and Nylander M. "Correlation of Dental Amalgam With Mercury in Brain Tissue." Journal of Prosthetic Dentistry, 58 (1987).
4) Schriever W and Diamond LE. "Electromotive Forces and Electric Currents Caused by Metallic Dental Fillings." Journal of 5) Dental Research, 31:205 (April 1952).
5) Solomon HA, Reinhard MC, and Goodale HI. "Pre-cancerous Lesions From Electrical Causes." Dental Digest, 39:149 (1933)
6) Wenetrup, et al. Brain Research 1990;53;125-131.

BACK