Debate about mercury fillings continues
BY DR. TERRY GAFF Saturday, 15 January 2011
There are lots of old sayings that are brought to mind by current events. For example, “Sleep tight — don’t let the bedbugs bite” seemed to have some relevance recently in many hotels and college dorms.
Another old phrase is “Mad as a Hatter.” For this one, you might think of the recent remake of “Alice in Wonderland” or perhaps the Teacup rides in the Disney theme parks. However, it makes me think of mercury.
In the past, they used mercury to create felt, from which hats were made. It is thought that the chronic exposure to mercury caused the “hatters” to become confused and demented, that is, to go “mad.”
Although mad hatters are a thing of the past, the concern about mercury continues to be an issue for many people because of mercury-based dental filling, known as dental amalgam, which has been used by dentists for many years.
In view of this concern, an advisory panel to the U.S. Food and Drug Administration (FDA) concluded recently that there are no huge scientific flaws in the agency’s 2009 finding that dental amalgam is safe for adults and children aged 6 years and older.
The FDA panel stated the opposite (as Dr. Gaff’s next paragraph indicates) Since there is little or no knowledge about how the amount of mercury reacts with children and the effect upon their brains which keep maturing into the early 20’s, saying it is safe for the subpopulation seems like a fairly large flaw. The FDA reference to kids 6 years and older is based upon absolutely nothing.
However, the dental products panel recommended that the FDA look at more data on the possible health risks that the filling material might pose to pregnant women and their fetuses and to young children, particularly nursing infants whose mothers have these fillings. The panel also said the agency should consider adding warnings for these groups to the material’s product instructions.
Representing the professionals who use the product, the American Dental Association maintains that dental amalgam is safe and needs no further regulation by the FDA as a medical device.
At the same time, the panel’s request for more scientific data about vulnerable populations acknowledged the concerns of dental amalgam opponents, who try to link mercury exposure to dozens of diseases ranging from autism to Alzheimer’s disease.
The way this sentence is framed makes it seem like the consumers don’t have any science on their side. A more accurate wording would have stated that “scientists presaented a mountain of peer reviewed scientific evidence (over 100 studies) that links long term exposure to mercury vapor (and particles) to Alzheimer’s Disease.” Please check the SCIENCE section of our website to see the many various adverse health effects from mercury vapor exposure, all referenced from studies in peer reviewed scientific journals.
It has already been established that at high enough levels, mercury exposure can damage the brain and kidneys. In fact, Norway, Sweden and Denmark have already banned the use of mercury-containing dental amalgam.
Mercury is not the only component of dental amalgam. It is composed of roughly 40 to 50 percent liquid elemental mercury and a powdered alloy of mostly silver, copper and tin.
The FDA believes that an individual with seven to ten amalgam fillings absorbs one to five micrograms of mercury per day. Amalgam opponents say this could be four times as high, meaning that tens of millions of people with these fillings could be at risk for health problems, based on the current reference exposure level (REL).
The FDA cites an ill-defined and unsubstantiated estimate of absorbed mercury exposure from dental amalgam of 1 to 5 μgs/day that supposedly relates to the presence of between 7 and 10 amalgam fillings.
This conclusion is attributed to a report by the Public Health Service publishedin 1993 (PHS, 1993). This cited report did not contain or conduct a detailed quantification of mercury exposure but based its estimates on the review of other yet older reports.
In fact, PHS(1993) acknowledged that estimates of mercury exposure from amalgam span 1 μg/day to 29μgs/day (see PHS, 1993, Appendix III), with higher estimates appropriately acknowledged for the sizable population of persons who have more than ten amalgam fillings.
Contrary to the FDA’s statement, the WHO Environmental Health Criteria 118 (WHO1991) did not “[find] that values generally in the range of 1-5 μg/day were estimated in theU.S. adult population”.
Rather, WHO (1991) concluded that “estimated average daily intake and retention” from dental amalgam was 3.8-21 (3-17) μg/day (values in brackets representingretained (absorbed) dose (WHO, 1991, Table 2).
Contrary to FDA’s assertion, the WHO (2003) did not conclude that “the highest estimate that WHO reports was a dose of 12 μgs/day, for middle-aged individuals with approximately 30 amalgam surfaces (Ref. 22)”.
In the Executive Summary of this document (WHO 2003), WHO clearly states “Dental amalgam constitutes a potentially significant source of exposure to elemental mercury, with estimates of daily intake from amalgam restorations ranging from 1 to 27 μg/day.”
Considering the FDA failed to do a proper risk assessment with their 2009 amalgam rule. The International Academy of Oral Medicine and Toxicology hired Mark G. Richardson, who devised the amalgam risk assessment for Health Canada in 1995, to do a proper amalgam risk assessment for the United States. What he found was that if one used the EPA MRL as a baseline then 63 million Americans are over the safe daily limit. If one was to use the California EPA MRL, then over 120 million Americans are over the safe daily limit. Long term exposure to mercury vapor is well established in the scientific literature to cause a wide range of health problems.
In addition, there is some question as to whether the FDA has set the REL too high because it was partially based on studies of industrial workers exposed simultaneously to mercury and chlorine gas, with the gas acting to reduce mercury exposure, thus skewing the numbers.
The panel called the chlorine gas argument a “red herring.”
Considering many of us were there, we have no recollection of the panel stating this. I could not find this anywhere in the testimony presented on the FDA website. This doesn’t mean a dentists (many of which were on the panel) didn’t say it. But this was NOT the stated viewpoint of the whole panel. Attribution for these kinds of comments would be helpful.
CORRECTION FROM MERCURY EXPOSURE: one panelist, not a dentist, but Susan Griffin PhD, of the Environmental Protection Agency (EPA), stated the chlorine arguement was a “red herring, “
Nevertheless, it advised the FDA to reexamine the scientific literature to reassess the REL and develop its own safe level for mercury exposure.
However, any change of the REL for mercury may have enormous consequences that extend far beyond the dentist’s office. This is because the Environmental Protection Agency uses the REL to regulate how much mercury that heavy industry can put into air and water, as well as to designate waste sites for its Superfund clean-up program. A lower REL could cost industries billions of dollars.
Health Canada states on its website that although dental amalgam generally does not pose a health threat, the primary teeth of children should be filled with a non-mercury material when feasible. Pregnant women, individuals allergic to mercury and those with impaired kidney function should avoid mercury-based fillings.
I believe Mark Richardson (the author of the Health Canada risk assessment, would disagree with this characterization and will soon post his response to your assertion because his 1995 risk assessment allowed 1 filling for a child and 4 for an adult. This is certainly not a no risk event.
With the concerns about mercury, you might be wondering why it is used in dentistry at all. It is because of the amalgam’s superiority over tooth-colored composite fillings for restoring multiple surfaces and for its greater durability. In addition, its lower price has made mercury-containing amalgam the default material for poorer patients, who might not be able to afford more expensive fillings if amalgam were banned.
There was lots of discussion on this point at the FDA hearing and it boiled down to 10% difference in longevity if composite were to be used in an old amalgam preparation which was never designed for composite. On the other hand if composite is used in what is called an A traumatic restoration then it is not only cheaper abut lasts longer.
Here is a quote for you to remember from Dr. Harold Loe, the Director of the National Institute of Dental Research ( NIDR), who stated in the September, 1993 edition of “Dental Products Report”: “That first filling is a critical step in the life of a tooth. Using amalgam for the first filling requires removing a lot of the tooth substance, not only diseased tooth substance but healthy tooth substance as well. So, in making the undercut you sacrifice a lot, and this results in a weakened tooth. The next thing you know the tooth breaks off, and you need a crown. Then you need to repair the crown…and so it continues to the stage where there is no more to repair and you pull the tooth. With the first filling you should do something that can either restore the tooth or retain more healthy tooth substance. Use new materials-composites or materials you can bond to the surface without undercuts. You can do this with little removal of the tooth substance so that the core of the tooth is still there.”
Of course, the best approach would be to prevent fillings with good dental care, including regular brushing, flossing and dental check ups. However, for most of us, even that fails occasionally.
If you are like me, you will count your fillings in the mirror before you even finish reading this column. You might even talk to your dentist about filling material options at your next dental appointment. However, rather than having my fillings drilled out and replaced, I plan to simply blame some of my “madness” on those fillings, whether they deserve it or not.
Dr. Terry Gaff practiced family medicine in Albion, Indiana for 17 years and is now medical director of the emergency department at Parkview Noble Hospital in Kendallville, Indiana and the Noble County EMS.
He is also the Noble County Coroner.
