Three scientific reasons amalgam fillings are unstable and result in high mercury exposures over time
Dental amalgam is about 50% mercury, but the mercury in amalgam is unstable and does not remain there for at least 3 reasons. Mercury is an unstable liquid at room temperature but remains so only temporarily unless contained by something like glass(plastic is not sufficient), since mercury vaporizes continuously to a gas at room temperature. This is only one of the reasons that amalgam is unstable, with significant levels of mercury vaporizing continuously, more when subjected to heat, chewing, or brushing. (www.flcv.com/periodon.html )
The 2nd and 3rd reasons that amalgam is unstable are galvanism (the battery effect) and EMF that people are all exposed to. Amalgam is composed of mixed metals, which in an electrolyte(saliva) form a battery and set up galvanic currents that pump mercury and other metals(tin, copper,etc.) into the oral cavity. From there it moves through the blood vessels and nerves to the brain, central nervous system, and other organs. The currents induced are significant, and can be measured by a meter, such as a microamp meter from Radio Shack by placing one probe on an amalgam tooth(or metal crown over amalgam) and the other probe on the upper hard palate of the individual tested.
Likewise everyone is subject to Electromagnetic Fields (EMF) exposure, through power lines in house and building walls or ceilings and from appliances, such as hair dryers, electric tooth brush, kitchen appliances, computers, etc. EMF induces currents in metals(the way that electricity is produced by a power plant) and does so in amalgam fillings and metal crowns over amalgam. Thus again significant currents that pump mercury and other toxic metals into the body can be measured by a microamp meter. (www.flcv.com/galv.html )
Due to these factors, those with several amalgam fillings receive high levels of mercury exposure, documented by medical labs to be on average about 5 to 10 times that of persons without amalgam. (www.flcv.com/damspr1.html) Also as documented by EPA and municipal sewer authorities, this results in high mercury exposure to those with amalgams, measured as on average approximately 30 micrograms per day excreted into sewers by a person with several amalgams. As a result, dental amalgam is by far the largest source of mercury in sewers and sewer sludge, with sewer sludge containing approximately 2 parts per million mercury on average (the EPA drinking water standard for mercury is 2 parts per billion, which is considered to not be enough to protect the public by some experts. The high levels of mercury in sewers and sewer sludge are significant factors in high mercury exposure to sewer plant workers, as well as the environment, including rivers, lakes, bays, and fish/wildlife. (www.flcv.com/damspr2.html) Many of Florida's seafood species contain high levels of mercury, and over 50% of water bodies have warnings to restrict fish consumption due to the high mercury levels. This is a significant health problem, to which amalgam is a significant contributor.
http://www.flcv.com/fishhg.html ( Bernard Windham, President, DAMS Intl )