In the United States, organizers of separate movements whose common aim is to drastically curtail or eliminate the use of dental amalgam have appealed their case in two different venues.

In one case, the Environmental Law Foundation (ELF) sought judicial relief in the State of California under Proposition 65 (the Safe Drinking Water and Toxic Enforcement Act of 1986), a State law requiring in-state businesses who employ 10 or more persons to warn consumers if they use chemicals known to cause birth defects or other reproductive harm. ELF's initial action—a notification of violation—in July 1993, targeted some 36 different dental amalgam manufacturers and distributors, and sought to require dental offices that purchased and used amalgam products to post warnings of reproductive toxicity in their offices. In December of that year, one manufacturer settled with the plaintiffs and agreed to include occupational warnings on its package containers and provide warning posters to customers for display in dental offices (the firm had actually begun this practice prior to commencement by ELF of formal legal action), in addition to paying $328,000 in penalties. The settlement agreement was sanctioned by the Superior Court of the State of California, County of San Francisco.

In September of the same year, a consortium of the remaining amalgam businesses, known as the Committee of Dental Amalgam Alloy Manufacturers, filed a motion in U.S. District Court, Southern District of California, seeking summary judgment on the grounds that the Federal medical device law, administered by the Food and Drug Administration, could not be preempted by state authorities. On August 23, 1994, the court granted declaratory and injunctive relief claims based on the argument for preemption.

By 1996, the ELF had successfully launched a challenge to the District Court ruling. In August 1996, the California Supreme Court overturned the ruling, thus reinstating the requirement that all dental offices with 10 or more employees had to post consumer warnings. An effort by the amalgam manufacturers committee to have the case reviewed by the U.S. Supreme Court was rejected in January 1997. Since then, both parties have been engaged in negotiations that will determine the practical obligation of dental amalgam suppliers and their customers to warn consumers. Because the majority of dental offices have fewer than 10 employees, ELF has reportedly advanced the position that amalgam manufacturers, which generally employ more than 10 persons, bear primary responsibility for warning customers and consumers. The practical effect of this argument, should it prevail, is that essentially all dental care providers would be responsible for posting warnings provided by amalgam suppliers to inform consumers that mercury is used in their offices and that mercury may cause birth defects or other reproductive harm.

The other major event is the filing of three separate citizen petitions with the Food and Drug Administration by several individual dentists and the American Academy of Head, Neck and Facial Pain. This action was prompted by a ruling by the U.S. District Court, Washington, DC, where one group had initially filed a lawsuit seeking judicially-directed regulatory action against dental amalgam, that the group had not exhausted available administrative remedies.

As a result, the group and others subsequently filed formal petitions seeking regulatory actions that range from an all-out ban of dental amalgam to use restrictions for certain sub-populations (e.g., pregnant women and young children) to required safety warnings in product labeling. In support of their requested actions, the petitioners referenced over 150 scientific publications, media articles, and miscellaneous material. As discussed in the previous section of this report, this information underwent rigorous scrutiny by dental and scientific experts from various USPHS agencies. The results of their reviews, described in that section, helped form the basis for FDA's response to each of three petitioners. FDA responded that it believes that dental amalgam should remain on the market and that the removal of the product without scientific justification could unnecessarily deny health professionals and consumers access to important products and disrupt the delivery of health care.

The debate over dental amalgam safety extends well beyond the borders of the United States; indeed, countries throughout the world are addressing the same concerns. Soon after release of the 1993 USPHS report, concerted efforts were initiated by the EHPC Working Group on Dental Amalgam to monitor the outcomes of other national risk assessments on dental amalgam, as well as to actively engage nations with an interest in the amalgam issue in multilateral consultations on policy-making, risk communication and product safety research relating to amalgam and currently available alternative materials.

These efforts have lead to several notable results. Chief among them is the ability and interest among a large number of industrialized nations to share new and relevant information from the scientific community and national regulatory bodies. It has also led other nations to solicit technical and policy advice from the USPHS in support of their own scientific and policy reviews on dental amalgam. Most importantly, this international dialogue has enhanced the efforts of the USPHS to maintain vigilance over world-wide developments.

Perhaps the single most enlightening feature of these discussions is that countries actively engaged in the dental amalgam issue are relying on the same body of science and dealing with very similar risk perception issues as are U.S. scientists and policy-makers. This common understanding has been reflected in various international forums and formal risk assessments, as described below.

Suggested by the USPHS and hosted by the German Federal Institute for Drugs and Medical Devices, this meeting brought together senior health officials from nine European countries, Canada and the U.S. Held in Berlin, the December 1994 meeting provided for an exchange of information on governmental policies, both extant and in process, on the use of dental amalgam and their underlying scientific rationales. Heralded by many of the participants as a much needed and long overdue event, the meeting was marked by candid discussions concerning the public health, environmental and dental care cost impacts of dental amalgam use, in addition to the health policy, regulatory, research, political, and risk communication implications of the issue. From these discussions emerged a consensus on the need for a continuation of periodic information exchanges on an international level, as well as the establishment of mechanisms for cross-sharing of adverse health reports attributed to amalgam restorations.

Participants at the Berlin meeting unanimously agreed to form a multi-nation steering committee to draft a conceptual framework for a second conference in terms of an agenda and means for expanding the number of participant nations, to identify possible meeting dates, and to solicit proposals from prospective host countries and make a site selection. The lead U.S. representative at the Berlin meeting and Chair of the EHPC Working Group on Dental Amalgam was designated as the leader of the steering committee. Within a year, the committee completed its work, circulated a final meeting prospectus to all of the nations represented at the inaugural meeting in Germany, and selected Sweden to host the second international conference. Planned for late 1997 or early 1998, the meeting is expected to focus on the latest science regarding dental amalgam safety and alternative materials, adverse incident reporting systems, risk communication techniques and an update on government policies relating to amalgam use.

According to information in a report by an ad hoc working group of the European Commission (EC), the Ministry of Environment issued an order (No. 520) on June 9, 1994, banning the sale of all mercury-containing products, including dental amalgam, as part of a move to enhance national environmental conditions. This action was not specifically aimed at dental amalgam nor was it predicated on known health effects associated with this particular product. In fact, the order permits the commercial distribution of dental restorative materials used for treating posterior teeth until January 1, 1999. It is also important to note that the prohibition order will not take effect until an adequate supply of clinically acceptable alternative restorative materials (i.e., non-amalgam substitutes) are widely available.

The EC report stated that in 1994, an expert group formed by the National Board of Health and Welfare in Sweden completed its investigation into the possible health effects from use of amalgam. The review was undertaken to determine if any changes to general recommendations on dental amalgam use issued by the National Board in 1991 warranted revision.

Among the conclusions drawn by the expert group were that:

"Scrutiny of the results of recent research... has not shown that mercury from amalgam has an adverse effect on health, with the exception of isolated cases of allergic reactions." "It is... the opinion of the expert group that there are at present no medical indications for recommending amalgam removal in order to relieve symptoms of general ill health."

Irrespective of this review, the national parliament of Sweden, has issued a non-binding recommendation that amalgam should not be used after January 1, 1997. This recommendation, which will undergo further evaluation in 1997, is part of an overall move to ban all mercury sources (e.g., chemical effluents, mercury thermometers and dental amalgam) as a means to safeguard the environment. In the interim, Sweden's Minister of Health and Social Affairs and its Association of County Councils have advised against the use of dental amalgam in children and young adults, unless individual patients needs dictate it.

On July 1, 1997, the German Ministry of Health, German Institute for Drugs and Medical Devices, Federal Dental Chamber, German Scientific Dental Association, German Association for Operative Dentistry and German Association of Dentists Practicing Neuropathy, issued a consensus statement on "Restorative Materials in Dentistry." The statement grew out of a national meeting aimed at addressing what the consensus statement purported is a "state of uncertainty by partly contradictory statements on amalgam and other dental filling materials." The statement made a number of recommendations, including:

"In general restorative materials are not to be used in those patients where an allergy against a component of the restorative materials has been demonstrated"

With respect to pregnant women, the report stated the following:

"An extensive filling therapy, exceeding emergency treatment (e.g., pain, lost filling), should be avoided for pregnant women. No amalgam fillings should be placed in or removed from the mouths of pregnant women, if possible. According to present knowledge, there is no evidence that the exposure of the unborn child to mercury released from the mother's amalgam fillings causes any health damage to the child.

In general, with pregnant women only short-lasting treatments should be performed, as diagnosis and therapy are only possible in a limited way. Glass ionomers, composers or similar materials may be used here as alternatives to amalgam."

The consensus statement also indicated that use of dental amalgam in people with severe renal dysfunctions is contraindicated and that dentists bear primary responsibility to decide whether to treat children with dental amalgam. The statement also made clear that while the German government is responsible for the evaluation and documentation of risks associated with dental amalgam and other marketed medical devices that bear the "EC mark" (i.e., the European Commission designation permitting free trade among EC Member States), dental professionals must decide on the appropriate use of the product based on the clinical needs of individual patients.

According to the EC report, an expert group on dental materials established by Austria's Federal Ministry of Health and Consumer Protection has recommended against the use of amalgam to treat deciduous teeth in children; use and removal of amalgam restorations in pregnant and lactating women; and replacement of existing amalgam fillings with other materials in patients exhibiting hypersensitivity to mercury.

The EC report also indicated that the Norwegian Board of Health has recommended the avoidance of "extensive amalgam therapy" in pregnant women.

As a result of negative press stories, in 1992 the Canadian government embarked upon a study of population exposure to mercury from dental amalgam, food and the environment and the relative contribution of amalgam to total exposure and the attendant risks from this one source. The study culminated in 1995, when Canada's Medical Devices Bureau released a preliminary report that was based solely on published literature and probabilistic modeling. On the basis of computer-derived exposure estimates, the draft report recommended a "tolerable daily intake (TDI) level" which varied by age and translated into a proposed limitation on the number of allowable amalgam fillings for individuals throughout their life cycle.

Canadian health officials formally sought and received technical consultation from the USPHS Working Group on Dental Amalgam. In brief, USPHS experts expressed reservations about the draft report because of the safety factors and other non-validated assumptions used to overcome uncertainties in the underlying data as the TDI was being calculated. The concerns registered by USPHS experts were echoed by individuals and organizations invited by the Canadian government to two stakeholder meetings. As a result, the dual concepts of instituting a TDI and imposing per capita restrictions on the number of dental amalgam restorations were re-examined and subsequently rejected. On August 21, 1996, the Canadian government released a revamped report that is fundamentally consistent with the 1993 USPHS report in several respects. First, the Canadian report concluded that:

"[D]ental amalgam contributes detectable amounts of mercury to the [human] body, and is the largest source of mercury exposure for average Canadians. However, this exposure is not causing illness in the general population." "Current evidence does not indicate that mercury contributes to Alzheimer's disease, amyotrophic lateral sclerosis, multiple sclerosis or Parkinson's disease."

The report went on to say that:

"... currently available clinical data are not reliable enough to permit making a confident estimate of a Tolerable Daily Intake for mercury from amalgam." "Evidence [also] does not warrant the removal of existing amalgam fillings from individuals who have no indications of adverse effects."

Also, like the position advocated by the USPHS, the Canadian report called for broader dentist-patient dialogue as it relates to dental treatments and for public accountability of solid risk-benefit information. And finally, the Canadian report recommended more directed, clinically relevant research on the safety of dental amalgam and alternative materials.

Notwithstanding the overarching conclusion that there is a lack of scientifically relevant and definitive evidence demonstrating a causal link between amalgam and adverse human health effects, the Canadian report, in contrast to the position of the USPHS, went on to prescribe clinical practice guidelines that encourage dental care providers to limit the use of amalgam in pregnant women, young children, and people with renal disease.

In 1996, the Wellington School of Medicine, University of Otago, in its capacity as a World Health Organization Collaborating Centre in Oral Health, completed a review of the available science regarding the potential health risks of using dental amalgam for tooth restorations. The review was performed for the New Zealand Ministry of Health. In a June 1996 draft consensus report, the four researchers offered a number of observations. The first of these is that:

"[D]espite a considerable volume of international research since 1992, the controversial aspects of amalgam mercury and health have not changed."

The researchers also commented that:

"[T]he greatest single deficiency in knowledge is the lack of analytical epidemiological data sufficiently impressive to test a link, or lack of it, between the contribution of amalgams to total mercury intake and numerous claimed mercury related ill-health effects."

Noting that 80 percent of all dental restorations received by New Zealanders are amalgam, the researchers concluded that:

"[W]hile data are available demonstrating higher body mercury burdens as an occupational effect in dental personnel, no evidence of higher prevalence of ill-health has emerged."

Of the four reviewers, three held the opinion that:

"...the assumption of a cause-and-effect relationship between amalgam and cases of ill-health is on evidence an overreaction and unwise, considering the endemic prevalence of amalgams in the population. The safety of alternative restorative materials themselves are less researched than amalgam."

"Continuing to implant or place dental amalgam in teeth appears sustainable on ethical grounds. Use of restorative materials (amalgam and others) in and on teeth does not contravene any code of practice... There is not enough evidence to warrant depriving the community of useful and reliable material. Suggestions of a massive, planned removal of amalgams is itself possibly unethical considering the public alarm, scale and cost of such an option weighed against the majority opinion of low to negligible risk. Patients should, however, always be fully informed of comparative risks and benefits before they accept any restorative material or treatment."

Under a directive from its legislature, the Canadian province of Quebec earlier this year completed an independent review of the safety of dental amalgam. In the resultant report, which took into account technical input offered by the membership of the EHPC Working Group on Dental Amalgam, it was found that:

"[T]he mainstream scientific view holds that mercury exposure, even the very low levels attributable to dental amalgam, might be affecting people adversely, but the evidence currently available is inadequate to determine if this is the case." "To date, no large studies of people whose main exposure is from dental amalgam have been carried out... Therefore, the existing evidence is weak, but the information base is inadequate to conclude that dental amalgam has no effects that might be of concern."

On the issue of alternative materials, the Quebec report noted that while some materials may be as well suited as amalgam depending upon the clinical circumstances, the:

"short- and long-term costs of all alternative restorative materials are substantially higher than the cost of amalgam…"

This fact, according to the report, is due to longer placement times, less durability, and thus more frequent need for replacements, and for some procedures, increased laboratory costs. Like other national assessments, the Quebec report cited the fact that:

"... the long-term health effects of the existing alternatives, and certainly the products under development, are only poorly known, if at all."

In summing up its report, the Quebec government indicated that if low-level mercury exposure from amalgam engenders adverse health effects, they are likely to be subtle, sub-clinical effects, and that more obvious health conditions and symptomatologies can probably not be linked to amalgam restorations. In addition, the Quebec report discourages removal of intact amalgams because of the lack of convincing evidence of any medical benefit. Instead, the report urges greater preventive and conservative dentistry and endorses the Health Canada report's call for prudence in placing amalgams in certain sub-populations.

In 1995, in the light of persistent questions within Europe about the safety of dental amalgam, the European Commission's Medical Devices Expert Group created an ad hoc working group and mandated it to examine all regulatory policies and administrative measures among Member States applying to amalgam as well as all relevant scientific information. The principal aim of this activity has been to arrive at a standardized policy for regulating dental amalgam, which the EC Medical Devices Directive (issued in 1995) treats as a medical device. With representation from each of the 16 EC Member States, along with participation by several prominent academicians as well as the USPHS in an observer capacity, the ad hoc group reached its final stage of deliberations in mid-1997. Among its draft conclusions were the following.

"All dental restorative materials including dental amalgam as well as its alternatives have the potential for causing some adverse re-actions and most contain components which may be toxic, usually at much higher doses than from this intended use." "In recent years, toxicological and biocompatibility aspects of dental amalgam have been reviewed extensively and risk analyses carried out. There are no data at present to indicate that mercury from dental amalgam fillings will cause an unacceptable health risk to the general population." "… no systemic toxic effects would be expected to arise from exposure to mercury at levels associated with the presence of dental amalgam fillings."

The draft report also observed that:

"Local reactions to dental amalgam fillings and other dental restorative materials do occur but are rare." "There is no scientific evidence that the use of dental amalgam is related to adverse effects on pre- and post-natal health or fertility." "There is no indication that clinically satisfactory dental amalgam fillings should be removed except in cases of a confirmed diagnosis of allergy to this material."

In addition to recommending additional research intended to definitively resolve the lingering debate over amalgam safety, special warnings in product labeling to avoid the use of dental amalgam in allergy-prone patients, and greater reporting by amalgam users of adverse incidents, the draft report made the following statement:

"There are no proven adverse effects on the fetus associated with the placement or presence of dental amalgam fillings in the mother. It is sensible, however, where clinically feasible, to minimize health interventions during pregnancy and avoid any unnecessary chemical exposure of the fetus. This precaution should be observed with the use of all dental materials."

The effect of this report, should it be adopted as written by the European Commission's Medical Device Expert Group, is not clear. Whether Member States will be permitted to promulgate and promote clinical practice recommendations within their own countries that are contrary to the EC findings and recommendations is also unclear.

In early March 1997, WHO sponsored a 1-week consultation meeting with international government officials, scientists, and representatives from the dental profession and dental trade industry. Co-chaired by the chair of the EHPC Working Group on Dental Amalgam, the main objectives of the meeting were to revisit its standing policy statement on dental amalgam and to forge an international research agenda related to amalgam and other restorative materials. The end product was a draft consensus statement that, with respect to the utility and safety of dental amalgam, made the following points.

"While much research has been devoted to the development of dental restorative materials, there is currently no direct filling material that has the wide indications for use, ease of handling and good physical properties of dental amalgam."

"Dental amalgam restorations are considered safe, but components of amalgam and other dental restorative materials may, in rare instances, cause local side effects or allergic reactions. The small amount of mercury released from amalgam restorations, especially during placement and removal, has not been shown to cause any other adverse health effects."

"While there has been a number of case studies and informal reports, no controlled studies have been published demonstrating systemic adverse effects from amalgam restorations. At present, there is no scientific evidence showing that general symptoms are relieved by the removal of amalgam restorations."

Participants at the WHO meeting also developed a prioritized research agenda that, among other things, calls for an internationally-based registry of biological and adverse health effects for all dental materials-related symptoms and diseases in various patient and occupational populations. To catalyze this new venture, an international advisory group, with representatives from the United States, Scandinavia, and Germany, was established and tasked with establishing a proposed structure for the registry and guidelines for user reporting of adverse events.

An interesting sidebar to the conference discussions was the mention of studies performed in Sweden in which patients with dental amalgam fillings, who claimed their physical ailments were caused by mercury toxicity, were monitored and medically evaluated. Although most of the results were not subjected to peer review, they are intriguing nonetheless.

One paper, for example, reported the results of a 3-year study of 234 patients, which was conducted in accordance with guidelines for the study of patients who associated their physical symptoms to amalgam, published in 1991 by Sweden's Social Welfare Board. The laboratory study involved medical (i.e., assessments of mercury levels in blood and urine) and odontological evaluations of each patient (three-fourths of the study population was women, with an average age of 49), conducted annually during the 3-year study period. The study was unable to demonstrate any significant statistical correlation between: (1) amalgam load and number of reported symptoms; (2) number of symptoms and mercury levels in blood; (3) amalgam load and symptoms commonly associated with mercury poisoning. The researchers concluded the following:

"In medical contexts, the majority of more frequent symptoms are generally regarded as being psychosomatic, or connected with the somatoform syndrome. Among approximately 12 percent of the patients with well defined diseases and where there has been a suspicion regarding a causal connection between illness and mercury…, there have been no scientific studies to confirm this as a fact. Nor does the psychosomatically dominated symptomology reported here constitute a specific image for either acute or chronic mercury poisoning." "Several epidemiological studies, [and] clinical studies, including our own, unequivocally indicate that on a group level, there is no connection between exposure to mercury from amalgam and the development of systemic symptoms of illness." "The result of the study shows that most patients exhibit a diffuse polysymptomatic status where we usually find a multifactorial background for this."