View Full Version : FDA To Look At Dental Amalgam Again

12-07-10, 08:15 PM
An advisory panel of the US Food and Drug Administration (FDA) next week will weigh a study claiming that 67 million Americans with mercury-based dental fillings are exposed to mercury levels exceeding those considered safe by the US Environmental Protection Agency (EPA).

The study, commissioned by an organization committed to mercury-free dentistry, also calls the EPA's safety threshold too high. It estimates that 122 million Americans with such fillings would be exposed to unsafe levels of mercury based on what it calls a more realistic threshold used by the California Environmental Protection Agency.

The advisory panel hearing, scheduled for December 14 and 15, promises to be another skirmish in this country's ongoing scientific war over the health risk of mercury-based cavity fillings — known as dental amalgam — that dates back to the mid-19th century, when it divided the dental profession. Declining dramatically in use during the last several decades, dental amalgam accounts for roughly 30% of all fillings as alternate materials have gained popularity, according to the American Dental Association (ADA). Nevertheless, the traditional filling still sparks controversy. Opponents blame it for causing the likes of autism, schizophrenia, and Alzheimer's disease.

Filling a cavity.
Silver-colored dental amalgam is composed of roughly 40% to 50% elemental metallic mercury, as opposed to the organic mercury compounds found in fish, or inorganic mercury compounds such as those used in batteries. The other ingredients of dental amalgam are silver, zinc, copper, and tin.

Elemental mercury releases mercury vapor that at high levels can damage the brain and kidneys, according to the FDA. However, the agency has maintained that dental amalgam is safe for filling cavities for adults and children aged 6 years and older. The ADA agrees, noting that combining mercury with other amalgam metals renders it stable and nontoxic.

A number of consumer and dental organizations do not share these views, however, and instead advocate banning dental amalgam, as Sweden, Norway, and Denmark have done. Even the FDA recently has tightened its controls over the material, which comes under the agency's regulatory oversight as a medical device. In July 2009, the agency bumped up its classification of dental amalgam from a lower-risk class II device to a moderate-risk class II device. That reclassification entailed label recommendations such as what dentists should tell patients about amalgam benefits and risks, including the risk of inhaling mercury vapor.

Among other things, the prescribed message states that "the developing neurological systems in fetuses and young children may be more sensitive to the neurotoxic effects of mercury vapor," although clinical information is scarce as to the long-term health outcomes. The agency has concluded that infants are not at risk if they are breast-fed by women exposed to mercury vapors from dental amalgam.

Amalgam opponents have petitioned the FDA to revisit its 2009 decision, which led to the scheduling of next weeks' hearing. The agency states that the dental products panel, part of its medical device advisory committee, will focus particularly on potential risks to pregnant women, fetuses, and young children. Issues that may come before the panel include the biocumulative effect of mercury and the adequacy of past clinical studies on dental amalgam.

The hearing next week raises the stakes for the product, considering how opponents have asked the agency to either ban it or classify it as a class III device — one that poses the highest risk to patients. The FDA has stated that class III designation probably would spell the demise of dental amalgam, because manufacturers would likely pull their products from their market instead of going through the time and expense of obtaining FDA premarket approval, as is required for class III devices. In essence, the premarket approval process would force them to prove that dental amalgam is safe.

The FDA can either accept or reject any recommendations that the dental advisory panel issues on the basis of its hearing next week.

Group Commissioning Study Advocates Removal of Amalgam Fillings

The fireworks at the hearing next week will likely be supplied by a study commissioned by the International Academy of Oral Medicine and Toxicology, one of several parties petitioning for the new FDA review. Based in ChampionsGate, Florida, the academy not only promotes mercury-free dentistry but also advocates that patients with amalgam fillings have them removed.

The group that conducted the study is the environmental division of a large, publicly traded engineering and construction firm in Ottawa, Canada, called SNC-Lavalin. The lead author, G. Mark Richardson, PhD, has previously authored similar studies for Health Canada, the Canadian equivalent of the US Department of Health and Human Services. That agency states that although dental amalgam generally does not pose a health threat, the primary teeth of children should be filled with a nonmercury material when appropriate. In addition, people with mercury allergies, pregnant women, and those with impaired kidney function should avoid mercury-based fillings, according to Health Canada.

Dr. Richardson's SNC-Lavalin study estimates mercury exposure for 5 different age groups ranging from toddlers to seniors. Four different exposure scenarios are set forward. The highest-exposure scenario assumes that all restored tooth surfaces are composed of dental amalgam; the lowest-exposure scenario assumes that 30% of persons with filled teeth have no amalgam, and the rest have amalgam in only half their fillings other than nonamalgam crowns.

Using the lowest-exposure scenario, Dr. Richardson estimates that because of the mercury vapor they inhale from dental-amalgam fillings, 67.2 million Americans exceed the mercury dose extrapolated from the reference exposure level (REL) of 0.3 µg/m3 set by the US EPA. However, Dr. Richardson writes that this REL is too high because the EPA based its math on studies of so-called chloralkali workers who make chlorine and caustic soda from brine solutions in a mercury-based process. For them, mercury toxicity would be reduced by simultaneous exposure to chlorine gas.

These chloralkali-worker studies also guided the California EPA in calculating its REL for elemental mercury, although its REL is 10 times lower, at 0.03 µg/m3. Dr. Richardson estimates that 122.3 million Americans with dental amalgam are exposed to mercury levels above this more conservative safety threshold. He notes that the REL set by Health Canada of 0.06 µg/m3 reflects studies of mercury exposure free of concomitant chlorine-gas exposure, making them more reliable.

According to the FDA, a dose that exceeds the REL set by the US EPA "does not necessarily mean that any adverse effect will occur."

Another recent study about mercury risk that the advisory panel may consider was published in the November issue of the Journal of Alzheimer's Disease. That study concludes that inorganic mercury, which the authors define as including elemental mercury, may be a cofactor in the development of Alzheimer's disease. The study, a meta-analysis of 106 other studies, recommended "the removal of mercury from public and ecologic circuits and replacing it wherever possible by less toxic alternatives."

FDA Must Consider Possible Fall-Out of Ban, Says ADA

The ADA has entered the latest fray over mercury and dental fillings, stating in comments filed with the FDA that "the best scientific evidence continues to support the safety of dental amalgam." No new research, it contends, has emerged to warrant new regulatory action since the FDA reclassification of dental amalgam last year. Meanwhile, the association faults amalgam opponents for citing research articles that are not peer reviewed or compliant with clinical trial standards, or else focused "solely on subclinical effects at the cellular level."

To bolster its case, the ADA referred to a report recently published by the World Health Organization that described dental amalgam's track record for safety in Europe and the United States. However, that report, titled "Future Use of Materials for Dental Restoration," smacks of faint praise, stating that "dental amalgam remains a dental restorative material of choice, in the absence of an ideal alternative." The report also recommends that the dental profession help identify safe and affordable substitutes as the use of amalgam is "phased down." A complete ban, the report states, "may not be realistic, practicable, and achievable."

The ADA raises similar points in its own defense of dental amalgam. "At present, there is no direct restorative material that works as well as amalgam for large fillings in the back teeth, in very deep fillings, or in fillings below the gum line," the association states in its FDA filing. Furthermore, current alternatives to amalgam cost more, meaning that a full or partial ban on the material would drive up the cost of dental restorations and price some individuals out of treatment.

"Any rational risk assessment must account for this side of the equation: the cost of regulation," the ADA states.

12-07-10, 08:16 PM
"Any rational risk assessment must account for this side of the equation: the cost of regulation," the ADA states.

Soooo, forgot the health costs associated with mercury; instead worry about the cost of regulation. That makes perfect sense!:sarcasm:

12-07-10, 08:58 PM
Well, come now, you know the FDA has a long proud history of keeping us safe, regulating salmonella in peanut butter factories, regulating sales of pastured beef, raw milk, vitamins and other supplements. I had to schedule my fall lambs at the slaughterhouse for the day when the FDA inspector would be on site to stamp the cuts of meat with his purple stamp, NOT FOR SALE. Really, who can we trust if not the FDA?

There is no smilie powerful enough to express my RAEG.