Somehow my personal reply from you got lost in my mailbox, so I decided to post this so everyone can read it.
I have more than a passing knowledge of both toxicology and epidemiology, having been involved in industrial health and safety, so I can speak with a certain amount of authority.
First of all, mercury is NOT toxic. You could swallow several grams of it and it would pass through the body unaltered and with no toxic effects. What IS toxic are some compounds of mercury, notably some organic compounds, known as organometallics. These are a cumulative CNS toxin. Some mercuric halides are also equally toxic, especially HgCl2.
This is taken from the http://www.toxicteeth.net/merctoxprofile.cfm
TOXICOLOGICAL PROFILE FOR MERCURY (UPDATE)
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
AGENCY FOR TOXIC SUBSTANCES AND DISEASE REGISTRY
MARCH 1999
EXCERPTS REGARDING THE HEALTH HAZARDS OF MERCURY AMALGAM FILLINGS:
Mercury is mined as cinnabar ore, which contains mercuric sulfide. Silver-colored dental fillings typically contain about 50% metallic mercury. These uses may pose a health risk from exposure to mercury both for the user and for other whom may be exposed to mercury vapors in contaminated air.
A potential source of exposure to metallic mercury for the general population is mercury released form dental amalgam fillings. The amalgam used in silver-colored dental fillings contains approximately 50% metallic mercury, 35% silver, 9% tin, 6% copper, and trace amounts of zinc. Very small amounts are slowly released from the surface of the filling due to corrosion or chewing or grinding motions. Part of the mercury at the surface of the filling may enter the air as mercury vapor or be dissolved in the saliva. The total amount of mercury released from dental amalgam depends upon the total number of fillings and surface of each filling. Estimates of the amount of mercury released from dental amalgams range from 3 to 17 micrograms per day (hg/day). The mercury from dental amalgam may contribute from 0 to more than 75% of your total daily mercury exposure. Sensitive populations may include pregnant women; children under the age of 6 (especially up to the age of 3), people with impaired kidney function, and people with hypersensitive immune responses to metals.
Mercury amalgams used for dental obturations are usually trinary alloys (sometimes ternary) and the mercury forms an intermetallic compound with the silver. The important point is that there is no free mercury in the alloy: it is all bound up with the silver in a distinctive eutectic phase which is formed in the first hours after mixing the components. This intermetallic compound has been shown to be virtually non-toxic under normal conditions found in the mouth, because the phase is non-reversible until it reaches liquidus (the temperature at which the phase reaches melting point, over 200°C). As neither silver nor mercury is amphoteric (ie, reacts with both acids and bases), the chances of any chemical decomposition in the pH range of saliva are very remote, indeed, unless you drink large quantities of, say, hydrochloric acid, in which case any oxidation of the amalgam surface could conceivably minute quantities of mercurous chloride or calomel, which is less toxic than mercuric chloride.
Seen from the above mercury it is obvious that amalgam is not a stable compound in your mouth "estimates of the amount of mercury released from dental amalgams range from 3 to 17 micrograms per day (hg/day)".
Toxicology is not an exact science, because different animals and even individuals react differently to toxins. Toxicologists therefore always err on the safe side, usually by decreeing a safe dose as a factor of one-tenth of the lowest dose known to have any toxic effect (sometimes one-third, in the case of substances with a long known history of the toxicology and epidemiology).
This is taken from http://www.toxicteeth.net/mercuryFillings.cfm
Mercury in dental-filling materials
–– an updated risk analysis in environmental medical terms
Professor Emeritus Maths Berlin
An overview of scientific literature published in 1997–2002 and current knowledge
Mercury is a potent toxin that affects the basic functions of the cell by bonding strongly with sulfhydryl and selenohydryl groups on albumen molecules in cell membranes, receptors and intracellular signal links, and by modifying the tertiary structure.
Seen from the above there is no doubt that mercury is a toxin no matter what the amount is, therefore there is no safe limit if you read the updated risk analysis from Maths Berlin.
It is also important to distinguish between acute, sub-chronic and chronic toxicity. Acute toxicity is the effect of a single exposure and is usually defined as LD50 (the lethal dose which will kill 50% of the subjects within 24 or 48 hours). This is obviously irrelevant to this discussion, as it implies very large doses. Chronic toxicity is the effect of extremely small doses over long periods of time, with cumulative toxins. The classic example is typified in the phrase, mad as a hatter. Hatters dressed beaver skins for top hats with mercury. As it has a vapour pressure at room temperature, they inhaled minute quantities of mercury vapour into the lungs for many years. Some of this reacted with the alveolar mucus and entered the blood stream and caused cumulative degeneration of parts of the brain. (To allay any arguments the mercury-silver intermetallic has zero vapour pressure at body temperature). Substances which cause cumulative degeneration of any tissue have a safe dosage based on (usually) the ponderal parts-per-million (ppm) or mg/m3 or µg/l, depending on the method of entry into the body.
To get to the point: there is quasi-zero risk of mercury poisoning from having amalgam fillings. There would be a risk of acute poisoning at the time of obturing the cavity, before the intermetallic phase is formed, but the quantities are too small for this risk to be serious and the metabolic disintegration of most of any ingested mercury would eliminate it in 24 hours through the faeces. Equally, there may be a minute acute risk if an existing filling is ground away, due to the high temperatures locally generated (for this reason, it is probably a mistake to remove existing fillings, certainly a plurality of them).
I would like to refer to http://www.iaomt.com/articledetails.cfm?artid=99.
In the late 1980's an experiment with sheep's and later on also monkeys where done. The physicians put radioactive mercury into the amalgam compound and used this as a filling in the sheep's and monkeys. Read the whole paper and get scared. This is really true and the really scaring thing is that the dentist organisation had/has the power to state this as bogus science and totally overrule the evident truth about the dangers of amalgam. When you say that the body easily eliminates all the mercury from the body I would say that no one, least of all the dentists, knows if the mercury is excreted from the body.
(To allay any arguments the mercury-silver intermetallic has zero vapour pressure at body temperature).
This cannot be true if it releases 3 - 17 ug/day of mercury into the air you breath. As the U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE states.
Modern fillings, based on UV-activated polymers are probably less toxic than mercury amalgams and are therefore preferable, but these have been developed only in the past couple of decades. There is therefore little reason for dentists to use mercury amalgams now, except in a few specific cases, where the synthetic fillings cannot hold mechanically.
The reason that mercury amalgam fillings are being actively discouraged or even banned now has nothing to do with patient safety. It is because the mixing process does release small amounts of mercury vapour which is cumulatively inhaled by the dentist and his staff: THEY are the ones at risk.
No, the primary reason is, that they know that they have made a major mistake by putting this toxic substance into peoples mouths making a large group chronically ill. Hopefully they will have to answer to all those who are daily being exposed and influenced by the amalgam.
Like in many cases, a little learning is a dangerous thing and there are a minority of cranks who believe that the very word mercury means toxics, without any scientific knowledge whatsoever. These guys, often ecopoliticians, cause much economic harm by their rants, concerning many more substances than just mercury. Ignore them.
By using technical expression you intimidate people who knows better and convinces those who does not know anything about this subject even though most of what you write is wrong. I don't know your reason for your interest in this matter, but I have my ideas. If you really want to know the truth about amalgam try to look into these links.
http://www.toxicteeth.org/mercuryFillings.cfm
http://www.iaomt.com/
http://www.melisa.org/
These homepages are the most serious information if you want get some knowledge on the amalgamissue.
