" I had mercury fillings in my teeth when I was younger, which I was then told was poisonous and had to be drilled out and replaced. Very pleasant."
Whoever told you that was misinformed or lying (maybe they wanted to profit by drilling them out and replacing them). Your fillings weren't "mercury". Your fillings were mercury/silver amalgam. An amalgam is an alloy that forms when mercury reacts chemically with silver. An alloy is a stable chemical compound. It does not spontaneously decompose into its constituents. If it did, your fillings would have dissolved and disappeared long ago.
Yes, when amalgam fillings are first placed you are exposed to some mercury vapor. That is why the ADA recommends that amalgam fillings should not be placed in small kids or pregnant women.
Amalgam is a very durable, long lasting restorative material that has been in use for over 100 years. Amalgam restorations normally last much longer than alternative materials such as tooth colored composites which require frequent maintenance/replacement. Did they tell you about that before they drilled out all your "mercury" fillings?
For the ADA position see latest info summarized here: http://www.ada.org/sections/pr...
The summary on page 2 says:
"In the six years since the LSRO report was published the identified research gaps have
not been completely addressed. However a number of studies have added to the
growing body of literature on the topic of amalgam safety. The findings of the studies
published between January 1, 2004 and June 15, 2010 showed no consistent evidence
of harm associated with dental amalgam fillings, including for infants and children. There
is some evidence that mercury excretion may be affected by gender. There was no
evidence demonstrating that some individuals are genetically susceptible to harmful
effects from exposure to the low doses of mercury associated with dental amalgam
fillings. Overall, studies continue to support the position that dental amalgam is a safe
restorative option for both children and adults. When responding to safety concerns it is
important to make the distinction between known and hypothetical risks. "