Mercury/Amalgams Article on Medscape Today from our IAOMT dentist

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http://www.medscape.com/medscapetoday

 

FDA Panel to Weigh Health Risk of Dental Amalgam Again

Lowes

Authors and Disclosures

December 7, 2010 †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.

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 , 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. '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. 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. 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. 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.

Authors and Disclosures

Journalist

Lowes

Freelance writer, St. Louis, Missouri

Disclosure: L. Lowes has disclosed no relevant financial relationships.

 

The link below is to the story that is on thefront page of today’s

Courier-Journal in Louisville, Ky. It is the states largest newspaper and is

owned by the Gannett Company which produces USA Today and many other

metropolitan papers across the country.

 http://www.courier-journal.com/article/20101205/FEATURES03/312020004/1008/NEWS\

01/Mercury%20fillings%20argument%20resurfaces?GID=1O4yLEMs254RdelvP0TxfzVgjgRG1z\

j1nZfRAt3Mt34%3D

 

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