Quackwatch Home Page

Analysis of U.S. Representative Diane Watson's Statement about
the "Mercury in Dental Filling Disclosure and Prohibition Act"

Robert S. Baratz, MD, DDS, PhD

On November 5, 2001, U.S. Representative Diane Watson (D-CA) issued a statement outlining her reasons for introducing a bill to outlaw the use of amalgam fillings. Amalgam use has been supported by the American Dental Association; the U.S. Public Health Service; the vast majority of dentists; the National Council Against Health Fraud; and Consumers Union, publisher of Consumer Reports magazine. Here is a segment-by-segment analysis of the fallacies involved in Watson's reasoning.

Watson says: In times like these, there are toxins that we don't know much about - how to control them, their source, and their impact. But there are toxins that we do know about -- toxins that we know do not belong in our bodies, toxins that we can do something about. My bill addresses that very problem.

Reality: A toxin is a naturally occurring compound, produced by living cells or organisms, that can cause disease when introduced into the body tissues. Botulinum toxin is an example. No form of mercury fits this definition.

Watson says: Mercury is an acute neuro-toxin. It is the most toxic non-radioactive element and the most volatile heavy metal. In recent years, it has been, or is being, removed from all health care uses, save one. Antibiotics have replaced oral doses of Mercury. The disinfectant Mercurochrome is banned. Recently, the Centers for Disease Control ordered Mercury preservatives removed from childhood vaccines. Mercury preservatives are no longer used in contact lens solutions.

Reality: The statement confuses the different forms of mercury. It is meaningless to make generalizations about toxicity without specifying chemical form, route of exposure, and duration of exposure. All forms of mercury are not neuro-toxins. Organic and inorganic forms of mercury have different properties. Of those compounds of mercury that are toxic, one must usually eat them for toxicity to occur. Most that are poisonous are organic mercurials, and most are not acutely poisonous. Dose always determines whether a substance is poisonous. Mercury and mercury compounds have several useful health-care applications. When properly handled, they are safe for their intended uses.

The difference between bound and unbound chemicals can be illustrated by a simple analogy. Elemental hydrogen is an explosive gas. Elemental oxygen is a gas that supports combustion. When combined, however, they form water, which has neither of these effects. Amalgam's ingredients are tightly bonded to each other. Although the types of chemical bonds in water and amalgam differ, saying that amalgam will poison you is just as wrong as saying that drinking water will make you explode and burst into flames.

Mercurochrome is a brand name for a product that formerly contained an organic mercurial. No study showed that its use as a simple topical antiseptic was harmful. Mercurochrome was removed from the market because it posed a safety hazard if accidentally swallowed by small children.

Watson says: This year, legislatures in California and several other states banned Mercury thermometers. When Governor Gray Davis signed bills addressing Mercury in thermometers and in dental fillings, he said, "Mercury is a persistent and toxic pollutant that bioaccumulates in the environment."

Reality: With all due respect, Governor Davis is neither a scientist or a clinician. Without characterizing the different forms of mercury, his statement is too general and vague to be understood. Mercury is an abundant element in the earth's crust and is found naturally in water, air, soil, and food. Additionally, Mercury is found in most solid fossil fuels and is released on their use. One must define type and quantity to ascertain if something is a "pollutant." One must also define what is meant by "pollutant." Water can be a pollutant if mixed in gasoline, for example.

Watson says: In recent years, the American Public Health Association, the California Medical Association, and Health Care Without Harm have all called for the elimination of putting any Mercury in the human body.

Reality: The American Public Health Association and the California Medical Association were not referring to the use of dental amalgam in fillings. Health Care Without Harm an alliance of groups primarily concerned with environmental issues and has no special expertise or standing in any debate about amalgam fillings. Searching its Web site, I found documents expressing concern about reducing the potential hazards of environmental mercury but nothing calling for the elimination of dental amalgam.

Watson says: Today, I am announcing legislation to disclose and phase-out the last major use of Mercury in the human body. The fillings that organized dentistry wrongly calls "silver" are mainly Mercury, not "silver."

Reality: Most amalgam fillings contain virtually no unreacted mercury. To say that amalgam fillings are "mainly mercury" is grossly misleading. It would be equivalent to saying that concrete is mostly cement and sand. While these ingredients are mixed with water to produce the concrete, they are modified and tightly bound together when the concrete hardens. In the same way, mercury is chemically modified and bound by the reaction that produces amalgam.

Watson says: Mercury is the major ingredient in each filling, about one-half gram per. In the words of Professor Boyd Haley of the University of Kentucky, that is a "colossal" amount of Mercury in scientific terms - as much, in fact, as is in a thermometer. A teenager with six fillings has six Mercury thermometers worth of Mercury in his or her mouth.

Reality: For the reasons stated above, these statements are false and misleading. Dr. Haley is neither a materials scientist nor a clinician. The statements regarding a "colossal" amount of mercury and about the teenager with six fillings are grossly misleading.

Watson says: The Mercury in the fillings is volatile, such that -- as all authorities concede -- poisonous vapors are constantly being emitted from the fillings, more so when one chews or passes hot liquid over the teeth. The Agency for Toxic Substances & Disease Registry of the United States Public Health Service reports that those poisonous vapors go first to the brain and kidneys. For the developing brain -- and by that I mean a child's brain -- a major health risk exists.

Reality: There is no credible scientific evidence that "poisonous vapors" are released from amalgam fillings or that that any patient has ever been "poisoned" by the mercury in amalgam fillings. ATSDR has made no such statement about dental amalgam. The agency has noted that although amalgam can contribute to body mercury exposure, this does not necessarily pose a health risk. ATSDR would like to see further research to explore whether any "subtle risks" have been overlooked. But -- based on current knowledge -- it does not advise against using dental amalgam [1].

Watson says: It is in fact children who are at greatest risk from these fillings. The government of Canada recommended back in 1996 that dentists not place fillings in the mouths of children or pregnant women. (The 1999 report on Mercury by the Agency for Toxic Substances & Disease Registry says Mercury passes through the placenta into the developing child's brain.) In 1997, a major manufacturer of dental amalgam, Dentsply, said that amalgam is CONTRAINDICATED (translation: DO NOT USE) for children and pregnant women, as well as for those with braces, Mercury hypersensitivities, or kidney problems. Another manufacturer, Vivadent, added a contraindication for nursing mothers. (That 1999 government report says the Mercury goes through the mother's breast milk into the baby.)

Reality: These statements seem to be confusing dental amalgam and mercury. Any medical device company is free to recommend how their product should be used as long as they do so within FDA regulations. Such recommendations should not be interpreted beyond their words. It is indeed likely that some of these recommendations were made to avoid frivolous lawsuits rather than to demonstrate any scientific fact. In our litigious society, companies often make recommendations for product use from the perspective of protecting business interests.

Watson says: Why don't consumers already know this? The answer is a disappointing one. Organized dentistry is extremely divided on this issue. My bill, in fact, is supported by the American Academy of Biological Dentistry.

Reality: The American Academy of Biological Dentistry should be regarded as a fringe group whose views are not shared by the vast majority of dentists.

Watson says: But the American Dental Association tells the public that the fillings are safe. The ADA does not tell the public that it accepts payments from the amalgam manufacturers while it pronounces their product safe. I wish to note that the American Medical Association has a policy prohibiting the organization from taking money for product endorsements. The ADA, by contrast, accepts money from the manufacturers of the products it endorses, which certainly hurts its credibility in my mind.

Reality: The ADA's "Seal of Acceptance" logo,signifies that a product meets ADA standards of safety and effectiveness. About 400 over-the-counter products and 900 professional products are involved. Participating manufacturers must submit the products for expert evaluation and agree to have their advertising preapproved. This program has served the public and the dental profession well for many years. It is irresponsible to imply that the ADA would endorse a dangerous product in order to make money.

Watson says: The public does not know about the presence of Mercury and its risks for two reasons. First, the fillings are falsely called "silver." This term is deceptive, because there is much more Mercury than silver in the product. It's time to call it what it is, and quit hiding the large presence of Mercury.

Reality: Some people know, some don't. There's really no reason for them to be concerned because amalgam does not pose a health hazard.

Watson says: Second, the ADA has a rule that gags dentists from talking about the risks of Mercury amalgam, a rule that some dental boards enforce against dentists who call for the elimination of Mercury in dental fillings. I understand that rule is being challenged by dentists in federal court in Maryland based on the First Amendment.

Reality: The ADA does not gag anyone. Its rules about ethical behavior forbid making false statements about dental materials. They simply say that to be ethical and continue to be a member of the ADA, one must not make false statements. The rules do not apply to nonmembers. Membership in the ADA is voluntary.

Watson says: State regulatory and licensing boards make their own rules and are independent of the ADA. A dental license is not a right but a privilege, regulated by a licensing board, usually appointed by the governor of a state. These boards are charged with protecting the public from inappropriate behavior of any licensee. Most dental practice acts and board rules prohibit making false and misleading statements to patients or the public.

Developments in this area have been quite encouraging this year in my state. In 1992, as a state Senator, I wrote a law that required the Dental Board of California to write a "Fact Sheet" about the "risks and efficacies" of dental fillings. My goal was to ensure the public could make informed choices about Mercury dental amalgam. But the Dental Board continued to ignore the law and, in recent years, defy the Davis Administration's insistence that it comply with this law.

Reality: The Dental Board published its fact sheet on October 17, 2001 [2]. The document provides up-to-date, factual information on the characteristics and uses and characteristics of all commonly used dental restorative materials. Among other things, it notes that there is no scientific evidence that amalgam fillings are toxic.

Watson says: After an impasse, including the Board refusing to show up for a hearing in Los Angeles on this issue, the Legislature stepped in and shut down the Board. I am told that never before has the California Legislature shut down a board before its Sunset date expired. In January, a new Dental Board will come into existence.

Reality: The existence of the dental board is regulated by state law. There has been no violation of state law reported. It would appear that the scientific position of the board did not satisfy the political agenda of the legislature. That does not make the board's science incorrect.

Watson says: A major environmental issue exists here. When removed from a patient's mouth, Mercury amalgam is a hazardous waste, and it is often improperly disposed of.

Reality: Mercury amalgam by itself is not hazardous. If the material is placed in an incinerator and decomposed by high heat back to elemental materials, and is subsequently mishandled, it can be harmful if accumulated in parts of the environment. The same can be said of flashlight batteries, used motor oil, used tires, and a host of other materials. Properly handled these materials are not hazardous.

Watson says: The more Mercury that goes into people's teeth, the more of it that will end up in our water supply. I am delighted, therefore, that San Francisco-based Clean Water Action is supporting my bill, and I look forward to other environmental groups joining us in this effort.

Reality: I know of no study which has demonstrated a connection between amalgam use and the concentration of mercury in our public water supply.

Watson says: The occupational risk is significant. Dental employees are constantly exposed to the vapors.

Reality: This statement is dead wrong. Common vapors in a dental office include latex, sulfur, eugenol, toothpaste, pumice, and various plastics. Many dental employees are not exposed to any vapors of any kind. The U.S. Occupational Safety and Health Administration (OSHA), which oversees workplace safety, has not classified dental offices as hazardous environments.

Watson says: Women in dental offices have lower fecundity (pregnancy) rates, more miscarriages, and more problem births; Mercury exposure is the likely reason.

Reality: The studies that suggested such a relationship made the relationship with nitrous oxide (laughing gas), not with mercury.

Watson says: Dentists have the highest suicide rate of any profession.

Reality: This statement is patently false. Police officers and prison guards are known to have high suicide rates. In comparison, dentists have a particularly low suicide rate. Among health professionals, psychiatrists have been reported to have the highest suicide rate.

Watson says: Depression leading to suicide is consistent with a diagnosis of Mercury toxicity.

Reality: Studies of mercury poisoning in industrial settings do not support this statement. While it is true that severely depressed patients have a risk of suicide, not all depressed patients are suicidal. Moreover, in cases of known industrial poisoning with mercury, depression was not the chief or dominant symptom. Further, this topic has nothing to do with dentistry, the practice of dentistry, dentists, dental personnel, or dental patients, because the amounts of mercury to which they are exposed are trivial.

Watson says: Mercury amalgam is dangerous before it is put in the mouth -- any dental journal will tell you that -- and it is considered hazardous waste after it has been removed. Who can conclusively say it's safe in between, when it is in our bodies?

Reality: Dental amalgam is not dangerous when mixed, as implied. Respected dental journals have never stated that dental amalgam is "dangerous." Amalgam scrap is "potentially hazardous" only if mishandled. So matches, household bleach, and many other common products that serve us well when used properly.

Watson says: A major social justice, or environmental justice, issue exists here. While the public lacks informed choice, low- and moderate-income people have it worse: they have no choice at all!

Reality: Every patient and every dentist has a choice of materials. Use of any particular material is not required by any regulatory body. Dentists have a professional duty to recommend appropriate treatment for their patients, consistent with their dental needs and sound dental practices.

Watson says: For families on Medi-Cal, the children get Mercury -- or nothing. It is outrageous that low-income Americans are forced to have such a toxic material put in their mouths.

Reality: Dental amalgam is not toxic, and no one forces anyone to have it.

Watson says: I understand that the Rhode Island legislature adopted a law this year to provide choice in insurance plans, and that the state of Maine permits Medicaid children to get alternatives to amalgam -- so, yes, we can do it differently. Mercury, and all other poisons in the body, hurt the body's immune system -- its ability to withstand diseases and biologically harmful agents.

Reality: Amalgam fillings have never been shown to harm anyone's immune system or produce any health problem except for local allergic reactions, which are very rare.

Watson says: If at any time in our nation's history we need strong immune systems, it is now. The stronger our bodies, the more able we are to fend off biological agents that have so tragically been placed in our midst. My bill will protect children, pregnant women, and nursing mothers immediately - regardless of their income. Henceforth, amalgam will bear warnings that they not be placed in these most vulnerable people. And there will be health warnings for all consumers of amalgam, also immediately.

Reality: Unless there is a hazard, there is no duty to warn. Amalgam has not been shown to be hazardous when used properly and correctly. There is no evidence or logical reason to believe that amalgam fillings have any effect on the immune system.

Watson says: Then, there is a five-year phase out of Mercury amalgam. That will give dentistry plenty of time to shift to alternatives that exist in today's market - resin, porcelain, and gold - or to develop new materials.

Reality: No dental material has been shown to be safer or better than dental amalgam for the applications for which it is intended to be used.

Watson says: Dentistry says amalgam is fine because it has been in use for 150 years. This statement makes no scientific sense.We have abandoned other remnants of pre-Civil War medicine, and we have abandoned all other uses of Mercury. It is no longer a question of if, but when, Mercury dental fillings will be history. I say five more years is time enough.

Reality: Extensive scientific reviews conducted over the past ten years by the FDA, Public Health Service, National Institutes of Health, the U.S. Centers for Disease Control and the American Dental Association, have concluded that dental amalgam is safe and effective [3-6]. Dentists rely upon these agencies to guide them regarding providing safe and useful materials for patients. These agencies are charged with protecting the public and have mustered the best minds and reviewed all available credible evidence in reaching their conclusions. The long history of use is significant because if a problem existed, it would have become clear long ago.

For Further Information


  1. Mercury. ATSDR Public Health Statement, March 1999.
  2. Dental Board of California. Dental materials fact sheet, adopted Oct 17, 2001.
  3. Benson JS and others. Dental Amalgam: A Scientific Review and Recommended Public Health Strategy for Research, Education and Regulation. Washington, D.C., 1993, US Public Health Service.
  4. Effects and side effects of dental restorative materials. Technology Assessment Conference Statement; 1991 Aug 26-28, 1991. Bethesda, MD: National Institutes of Health, Office of Medical Applications of Research 9:18., 1991.
  5. Working Group on Dental Amalgam. Review of dental amalgam mercury scientific literature. FDA Office of Science and Technology Annual Report, 1997.
  6. ADA Council on Scientific Affairs. Dental amalgam: Update on safety concerns. Journal of the American Dental Association 129:494-501, 1998.


Dr. Baratz is president of the National Council Against Health Fraud. He has extensive training and practical experience in internal medicine, emergency medicine, oral medicine, dentistry, material science, and research methodology. In addition to practicing medicine and dentistry, he serves as a medical and dental consultant to many state licensing boards, federal agencies, insurance companies, and the legal profession.

Quackwatch Home Page

This article was revised on November 13, 2001.