But are they?
You can find a lot of material on the web related to this topic - the vast majority to me seems to indicate that amalgam fillings are poisoning you. But there are some problems with the arguments for widespread mercury poisoning form amalgam fillings.
(This war was already fought in the 1840's and 50's just after the use of amalgam was brought to the US from France. Initially it was considered quackery by the established dentists (American Society of Dental Surgeons) who hammered "hot gold" into the tooth cavity. Eventually amalgam won out and was endorsed by the American Dental Society in 1850.)
What's most interesting to me are these facts:
Amalgam fillings have been in constant use for at least 150 years. During this time not only do the recipients of amalgam filling have exposure to some level of mercury, but so do the dental providers installing these fillings.
Mercury is supposedly linked to autism and vaccines - yet autism has increased while use of amalgam filling has decreased during the last 30 or so years.
Amalgam fillings offer a degree of active suppression of further decay once installed.
There are a lot of pro and con studies related to this that are summarized here.
So what's the truth here?
First of all mercury is clearly bad for you and there is no minimum dose considered safe. Mercury is fat soluble and once ingested is enters the body and organs it a way that makes removing it difficult. Mercury easily passes the blood/brain barrier and can enter the brain to cause mental impairment. It also can easily pass via breast milk from mother to child.
No one disagrees on this.
Then there is the amalgam itself:
Modern dental amalgam consist of (from Wikipedia):
- > 40% silver (Ag)
- < 32% tin (Sn)
- < 30% copper (Cu)
- < 2% zinc (Zn)
- < 3% mercury (Hg)
For a filling of amalgam weighing one gram there would be about 30 mg (or 30,000 ug) of Mercury.
Now consider that you are not eating the filling - its installed in your mouth where it may live for 50 years. So consider the following from that perspective:
According to the EPA (from this) "[The] EPA's methylmercury reference dose is .1 micrograms/kg body weight per day. In July 2000, the National Academy of Sciences found the EPA's reference dose as "scientifically justifiable" for protecting most Americans."
For a 200 pound man (approx. 90 kg) 90kg x .1 ug/kg = 9 ug of mercury per day or 63 ug of mercury per week. (1 ug is one millionth of a gram.)
The WHO reports (mentioned here) that people inhale mercury from amalgam fillings at a daily rate of 3 to 17 ug per day.
Thimeresol in some vaccines for chldren (given an average western vaccine regiment) means a does of 25 ug/vaccine for at least a dozen vaccines.
Your diet probably includes at least 15 ug of mercury per day without eating anything special (like fish).
I doubt there would be much disagreement on these facts and the conclusion from them is Mercury, at a rate of probably 8 - 30 ug's, enters your body daily from a variety of sources if you have amalgam fillings. It also leaves your body daily at some measurable rate.
What is disputed is what, if any, effect the inhaled or injected mercury has on an individual. (There is a corresponding argument for dental professionals exposed to mercury but we are not focusing on that here.)
Here there is very, very little agreement.
Both those for and against amalgam vaccines claim the other side is using quackery instead of science to support their position: The "Amalgam is Toxic" Quackery (also here) and The "Amalgam is Not Toxic" Quackery.
The FDA and the American Dental Society believe and say (as recently as 2008) that amalgam fillings are safe and that there isn't any scientific reason to ban or otherwise alter their usage.
The bottom line for me here has to be the "history"...
A century and a half of continuous usage (and dental hygiene today is not what it was 50 years ago, i.e., more amalgam fillings then than today where only about 50% of fillings are amalgam) tells me that its likely that though fillings out-gas mercury (along with any that you might ingest with dental work) you are probably still "safe" from mercury - whatever that means. Since we ingest some mercury every day its likely our bodies can, to a certain extent, handle it.
There is also a hysterical element to the "Anti-Amalgamists" - claiming various "cures" for a large variety of vague problems solved only by having all of their fillings replaced. Certainly there are documented allergies to amalgam - but they are very few. This side is not well documented and populated mostly by anecdotal claims of healing - I need more than this and more than studies telling me that mercury passes through me on a daily basis.
Personally I don't plan to have my amalgam fillings ripped out anytime soon...
But then I always live dangerously.